Web3

This is the main (or ‘umbrella’) class of the web3.js library.

                                var Web3 = require('web3');                             
                                    > Web3.utils
                                    > Web3.version
                                    > Web3.givenProvider
                                    > Web3.providers
                                    > Web3.modules

Web3.modules

   Web3.modules

Will return an object with the classes of all major sub modules, to be able to instantiate them manually.

Returns¶

Object: A list of module constructors:

Eth - Constructor: The Eth module for interacting with the Ethereum network (web3.eth).
Net - Constructor: The Net module for interacting with network properties (web3.eth.net).
Personal - Constructor: The Personal module for interacting with the Ethereum accounts (web3.eth.personal).
Shh - Constructor: The Shh module for interacting with the whisper protocol (web3.shh).
Bzz - Constructor: The Bzz module for interacting with the swarm network (web3.bzz).

Example¶

 Web3.modules
                                   
                 > {
                       Eth: Eth(provider),
                       Net: Net(provider),
                       Personal: Personal(provider),
                       Shh: Shh(provider),
                       Bzz: Bzz(provider),
                 }

Web3 Instance ¶

The Web3 class is an umbrella package to house all Ethereum related modules.

var Web3 = require('web3');

           // "Web3.providers.givenProvider" will be set if in an Ethereum supported browser.
           var web3 = new Web3(Web3.givenProvider || 'ws://some.local-or-remote.node:8546');
                                            
           > web3.eth
           > web3.shh
           > web3.bzz
           > web3.utils
           > web3.version

version¶

Static accessible property of the Web3 class and property of the instance as well.

          Web3.version
          web3.version

Contains the current package version of the web3.js library.

Returns¶

String: The current version.

Example¶

          web3.version;
          > "1.2.3"

utils¶

Static accessible property of the Web3 class and property of the instance as well.

         Web3.utils
         web3.utils

Utility functions are also exposes on the Web3 class object directly.

See web3.utils for more.

setProvider¶


                                web3.setProvider(myProvider)
         web3.eth.setProvider(myProvider)
         web3.shh.setProvider(myProvider)
         web3.bzz.setProvider(myProvider)
         ...

Will change the provider for its module.

Note

When called on the umbrella package web3 it will also set the provider for all sub modules web3.eth, web3.shh, etc. EXCEPT web3.bzz which needs a separate provider at all times.

Parameters¶

Object - myProvider: a valid provider.

Returns¶

Boolean

Example: Local Geth Node¶


                                var Web3 = require('web3');
         var web3 = new Web3('http://localhost:8545');
         // or
         var web3 = new Web3(new Web3.providers.HttpProvider('http://localhost:8545'));
                                                
         // change provider
         web3.setProvider('ws://localhost:8546');
         // or
         web3.setProvider(new Web3.providers.WebsocketProvider('ws://localhost:8546'));
                                                
         // Using the IPC provider in node.js
         var net = require('net');
         var web3 = new Web3('/Users/myuser/Library/Ethereum/geth.ipc', net); // mac os path
         // or
         var web3 = new Web3(new Web3.providers.IpcProvider('/Users/myuser/Library/Ethereum/geth.ipc', net)); // mac os path
         // on windows the path is: "\\\\.\\pipe\\geth.ipc"
         // on linux the path is: "/users/myuser/.ethereum/geth.ipc"

Example: Remote Node Provider¶


                                // Using a remote node provider, like Alchemy (https://www.alchemyapi.io/supernode), is simple.
         var Web3 = require('web3');
         var web3 = new Web3("https://eth-mainnet.alchemyapi.io/v2/your-api-key");

providers¶


                                web3.providers
         web3.eth.providers
         web3.shh.providers
         web3.bzz.providers
         ...

Contains the current available providers.

Value¶

Object with the following providers:

Object - HttpProvider: HTTP provider, does not support subscriptions.

Object - WebsocketProvider: The Websocket provider is the standard for usage in legacy browsers.

Object - IpcProvider: The IPC provider is used node.js dapps when running a local node. Gives the most secure connection.

Example¶


                                var Web3 = require('web3');
         // use the given Provider, e.g in Mist, or instantiate a new websocket provider
         var web3 = new Web3(Web3.givenProvider || 'ws://remotenode.com:8546');
         // or
         var web3 = new Web3(Web3.givenProvider || new Web3.providers.WebsocketProvider('ws://remotenode.com:8546'));
                                                            
         // Using the IPC provider in node.js
         var net = require('net');
                                                            
         var web3 = new Web3('/Users/myuser/Library/Ethereum/geth.ipc', net); // mac os path
         // or
         var web3 = new Web3(new Web3.providers.IpcProvider('/Users/myuser/Library/Ethereum/geth.ipc', net)); // mac os path
         // on windows the path is: "\\\\.\\pipe\\geth.ipc"
         // on linux the path is: "/users/myuser/.ethereum/geth.ipc"

Configuration¶


                                // ====
         // Http
         // ====
                                                            
         var Web3HttpProvider = require('web3-providers-http');
                                                           
         var options = {
            keepAlive: true,
            withCredentials: false,
            timeout: 20000, // ms
            headers: [
                {
                   name: 'Access-Control-Allow-Origin',
                    value: '*'
                },
                {
                      ...
                    }
                ],
                agent: {
                     http: http.Agent(...),
                     baseUrl: ''
                }
            };
                                                             
            var provider = new Web3HttpProvider('http://localhost:8545', options);
                                                            
            // ==========
            // Websockets
            // ==========
                                                            
            var Web3WsProvider = require('web3-providers-ws');
                                                            
            var options = {
                timeout: 30000, // ms
                                                            
                // Useful for credentialed urls, e.g: ws://username:password@localhost:8546
                headers: {
                    authorization: 'Basic username:password'
                },
                                                            
                clientConfig: {
                    // Useful if requests are large
                    maxReceivedFrameSize: 100000000,   // bytes - default: 1MiB
                    maxReceivedMessageSize: 100000000, // bytes - default: 8MiB
                                                            
                    // Useful to keep a connection alive
                    keepalive: true,
                    keepaliveInterval: 60000 // ms
            },
                                                            
            // Enable auto reconnection
            reconnect: {
                    auto: true,
                    delay: 5000, // ms
                    maxAttempts: 5,
                    onTimeout: false
                }
            };
                                                            
            var ws = new Web3WsProvider('ws://localhost:8546', options);

More information for the Http and Websocket provider modules can be found here:

givenProvider¶


                                web3.givenProvider
            web3.eth.givenProvider
            web3.shh.givenProvider
            web3.bzz.givenProvider
            ...

When using web3.js in an Ethereum compatible browser, it will set with the current native provider by that browser. Will return the given provider by the (browser) environment, otherwise null.

Returns¶

Object: The given provider set or null;

Example¶

currentProvider¶


                                web3.currentProvider
            web3.eth.currentProvider
            web3.shh.currentProvider
            web3.bzz.currentProvider
            ...

Will return the current provider, otherwise null.

Returns¶

Object: The current provider set or null.

Example¶

BatchRequest¶


                                new web3.BatchRequest()
            new web3.eth.BatchRequest()
            new web3.shh.BatchRequest()
            new web3.bzz.BatchRequest()

Class to create and execute batch requests.

Parameters¶

none

Returns¶

Object: With the following methods:

add(request): To add a request object to the batch call.
execute(): Will execute the batch request.

Example¶


                            var contract = new web3.eth.Contract(abi, address);

            var batch = new web3.BatchRequest();
            batch.add(web3.eth.getBalance.request('0x0000000000000000000000000000000000000000', 'latest', callback));
            batch.add(contract.methods.balance(address).call.request({from: '0x0000000000000000000000000000000000000000'}, callback2));
            batch.execute();

extend¶


                                web3.extend(methods)
            web3.eth.extend(methods)
            web3.shh.extend(methods)
            web3.bzz.extend(methods)
            ...

Allows extending the web3 modules.

Note

You also have *.extend.formatters as additional formatter functions to be used for input and output formatting. Please see the source file for function details.

Parameters¶

methods - Object: Extension object with array of methods description objects as follows:
- property - String: (optional) The name of the property to add to the module. If no property is set it will be added to the module directly.
- methods - Array: The array of method descriptions:
  
  name - String: Name of the method to add.
  
  call - String: The RPC method name.
  
  params - Number: (optional) The number of parameters for that function. Default 0.
  
  inputFormatter - Array: (optional) Array of inputformatter functions. Each array item responds to a function parameter, so if you want some parameters not to be formatted, add a null instead.
  
  outputFormatter - ``Function: (optional) Can be used to format the output of the method.

Returns¶

Object: The extended module.

Example¶


                                web3.extend({
                 property: 'myModule',
                 methods: [{
                     name: 'getBalance',
                     call: 'eth_getBalance',
                     params: 2,
                     inputFormatter: [web3.extend.formatters.inputAddressFormatter, web3.extend.formatters.inputDefaultBlockNumberFormatter],
                     outputFormatter: web3.utils.hexToNumberString
                 },{
                     name: 'getGasPriceSuperFunction',
                     call: 'eth_gasPriceSuper',
                     params: 2,
                     inputFormatter: [null, web3.utils.numberToHex]
                 }]
             });
                                                                       
             web3.extend({
                 methods: [{
                     name: 'directCall',
                     call: 'eth_callForFun',
                 }]
             });
                                                                        
             console.log(web3);
             > Web3 {
                 myModule: {
                     getBalance: function(){},
                     getGasPriceSuperFunction: function(){}
                 },
                 directCall: function(){},
                 eth: Eth {...},
                 bzz: Bzz {...},
                 ...
             }

Section-2

web3.eth¶

The web3-eth package allows you to interact with an Ethereum blockchain and Ethereum smart contracts.


                                var Eth = require('web3-eth');

            // "Eth.providers.givenProvider" will be set if in an Ethereum supported browser.
            var eth = new Eth(Eth.givenProvider || 'ws://some.local-or-remote.node:8546');
                                                                  
                                                                    
            // or using the web3 umbrella package
                                                                 
            var Web3 = require('web3');
            var web3 = new Web3(Web3.givenProvider || 'ws://some.local-or-remote.node:8546');
                                                                    
            // -> web3.eth

Note on checksum addresses¶

All Ethereum addresses returned by functions of this package are returned as checksum addresses. This means some letters are uppercase and some are lowercase. Based on that it will calculate a checksum for the address and prove its correctness. Incorrect checksum addresses will throw an error when passed into functions. If you want to circumvent the checksum check you can make an address all lower- or uppercase.

Example¶


                                web3.eth.getAccounts(console.log);
            > ["0x11f4d0A3c12e86B4b5F39B213F7E19D048276DAe" ,"0x85F43D8a49eeB85d32Cf465507DD71d507100C1d"]

subscribe¶

For web3.eth.subscribe see the Subscribe reference documentation.

Contract¶

For web3.eth.Contract see the Contract reference documentation.

Iban¶

For web3.eth.Iban see the Iban reference documentation.

personal¶

For web3.eth.personal see the personal reference documentation.

accounts¶

For web3.eth.accounts see the accounts reference documentation.

ens¶

For web3.eth.ens see the ENS reference documentation.

abi¶

For web3.eth.abi see the ABI reference documentation.

net¶

For web3.eth.net see the net reference documentation.

setProvider¶


                                web3.setProvider(myProvider)
            web3.eth.setProvider(myProvider)
            web3.shh.setProvider(myProvider)
            web3.bzz.setProvider(myProvider)
            ...

Will change the provider for its module.

Note

When called on the umbrella package web3 it will also set the provider for all sub modules web3.eth, web3.shh, etc. EXCEPT web3.bzz which needs a separate provider at all times.

Parameters¶

Object - myProvider: a valid provider.

Returns¶

Boolean

Example: Local Geth Node¶


                                var Web3 = require('web3');
            var web3 = new Web3('http://localhost:8545');
            // or
            var web3 = new Web3(new Web3.providers.HttpProvider('http://localhost:8545'));
                                                                        
            // change provider
            web3.setProvider('ws://localhost:8546');
            // or
            web3.setProvider(new Web3.providers.WebsocketProvider('ws://localhost:8546'));
                                                                       
            // Using the IPC provider in node.js
            var net = require('net');
            var web3 = new Web3('/Users/myuser/Library/Ethereum/geth.ipc', net); // mac os path
            // or
            var web3 = new Web3(new Web3.providers.IpcProvider('/Users/myuser/Library/Ethereum/geth.ipc', net)); // mac os path
            // on windows the path is: "\\\\.\\pipe\\geth.ipc"
            // on linux the path is: "/users/myuser/.ethereum/geth.ipc"

Example: Remote Node Provider¶


                                // Using a remote node provider, like Alchemy (https://www.alchemyapi.io/supernode), is simple.
            var Web3 = require('web3');
            var web3 = new Web3("https://eth-mainnet.alchemyapi.io/v2/your-api-key");

providers¶


                                web3.providers
            web3.eth.providers
            web3.shh.providers
            web3.bzz.providers
            ...

Contains the current available providers.

Value¶

Object with the following providers:

Object - HttpProvider: HTTP provider, does not support subscriptions.
Object - WebsocketProvider: The Websocket provider is the standard for usage in legacy browsers.
Object - IpcProvider: The IPC provider is used node.js dapps when running a local node. Gives the most secure connection.

Example¶


                                var Web3 = require('web3');
            // use the given Provider, e.g in Mist, or instantiate a new websocket provider
            var web3 = new Web3(Web3.givenProvider || 'ws://remotenode.com:8546');
            // or
            var web3 = new Web3(Web3.givenProvider || new Web3.providers.WebsocketProvider('ws://remotenode.com:8546'));
                                                                              
            // Using the IPC provider in node.js
            var net = require('net');
                                                                               
            var web3 = new Web3('/Users/myuser/Library/Ethereum/geth.ipc', net); // mac os path
            // or
            var web3 = new Web3(new Web3.providers.IpcProvider('/Users/myuser/Library/Ethereum/geth.ipc', net)); // mac os path
            // on windows the path is: "\\\\.\\pipe\\geth.ipc"
            // on linux the path is: "/users/myuser/.ethereum/geth.ipc"

Configuration¶


                                // ====
            // Http
            // ====
                                                                                    
            var Web3HttpProvider = require('web3-providers-http');
                                                                                    
            var options = {
                 keepAlive: true,
                 withCredentials: false,
                 timeout: 20000, // ms
                 headers: [
                     {
                         name: 'Access-Control-Allow-Origin',
                         value: '*'
                     },
                     {
                         ...
                     }
                 ],
                 agent: {
                     http: http.Agent(...),
                     baseUrl: ''
                 }
            };
                                                                                    
            var provider = new Web3HttpProvider('http://localhost:8545', options);
                                                                                    
            // ==========
            // Websockets
            // ==========
                                                                                    
            var Web3WsProvider = require('web3-providers-ws');
                                                                                    
            var options = {
                 timeout: 30000, // ms
                                                                                    
                 // Useful for credentialed urls, e.g: ws://username:password@localhost:8546
                 headers: {
                     authorization: 'Basic username:password'
                 },
                                                                                    
                 clientConfig: {
                     // Useful if requests are large
                     maxReceivedFrameSize: 100000000,   // bytes - default: 1MiB
                     maxReceivedMessageSize: 100000000, // bytes - default: 8MiB
                                                                                    
                     // Useful to keep a connection alive
                     keepalive: true,
                     keepaliveInterval: 60000 // ms
                 },
                                                                                    
                 // Enable auto reconnection
                 reconnect: {
                     auto: true,
                     delay: 5000, // ms
                     maxAttempts: 5,
                     onTimeout: false
                 }
            };
                                                                                    
            var ws = new Web3WsProvider('ws://localhost:8546', options);

More information for the Http and Websocket provider modules can be found here:

givenProvider¶


                                    web3.givenProvider
            web3.eth.givenProvider
            web3.shh.givenProvider
            web3.bzz.givenProvider
            ...

When using web3.js in an Ethereum compatible browser, it will set with the current native provider by that browser. Will return the given provider by the (browser) environment, otherwise null.

Returns¶

Object: The given provider set or null;

Example¶

currentProvider¶


                                    web3.currentProvider
            web3.eth.currentProvider
            web3.shh.currentProvider
            web3.bzz.currentProvider
            ...

Will return the current provider, otherwise null.

Returns¶

Object: The current provider set or null.

Example¶

BatchRequest¶


                                    new web3.BatchRequest()
            new web3.eth.BatchRequest()
            new web3.shh.BatchRequest()
            new web3.bzz.BatchRequest()

Class to create and execute batch requests.

Parameters¶

none

Returns¶

Object: With the following methods:

add(request): To add a request object to the batch call.
execute(): Will execute the batch request.

Example¶


                                    var contract = new web3.eth.Contract(abi, address);

            var batch = new web3.BatchRequest();
            batch.add(web3.eth.getBalance.request('0x0000000000000000000000000000000000000000', 'latest', callback));
            batch.add(contract.methods.balance(address).call.request({from: '0x0000000000000000000000000000000000000000'}, callback2));
            batch.execute();

extend¶


                                    web3.extend(methods)
            web3.eth.extend(methods)
            web3.shh.extend(methods)
            web3.bzz.extend(methods)
            ...

Allows extending the web3 modules.

Note

You also have *.extend.formatters as additional formatter functions to be used for input and output formatting. Please see the source file for function details.

Parameters¶

methods - Object: Extension object with array of methods description objects as follows:
- property - String: (optional) The name of the property to add to the module. If no property is set it will be added to the module directly.
- methods - Array: The array of method descriptions:
  
  name - String: Name of the method to add.
  
  call - String: The RPC method name.
  
  params - Number: (optional) The number of parameters for that function. Default 0.
  
  inputFormatter - Array: (optional) Array of inputformatter functions. Each array item responds to a function parameter, so if you want some parameters not to be formatted, add a null instead.
  
  outputFormatter - ``Function: (optional) Can be used to format the output of the method.

Returns¶

Object: The extended module.

Example¶


                                    web3.extend({
                 property: 'myModule',
                 methods: [{
                     name: 'getBalance',
                     call: 'eth_getBalance',
                     params: 2,
                     inputFormatter: [web3.extend.formatters.inputAddressFormatter, web3.extend.formatters.inputDefaultBlockNumberFormatter],
                     outputFormatter: web3.utils.hexToNumberString
                 },{
                     name: 'getGasPriceSuperFunction',
                     call: 'eth_gasPriceSuper',
                     params: 2,
                     inputFormatter: [null, web3.utils.numberToHex]
                 }]
            });
                                                                                                    
            web3.extend({
                 methods: [{
                     name: 'directCall',
                     call: 'eth_callForFun',
                 }]
            });
                                                                                                    
            console.log(web3);
            > Web3 {
                 myModule: {
                     getBalance: function(){},
                     getGasPriceSuperFunction: function(){}
                 },
                 directCall: function(){},
                 eth: Eth {...},
                 bzz: Bzz {...},
                 ...
            }

defaultAccount¶


                                    web3.eth.defaultAccount

This default address is used as the default "from" property, if no "from" property is specified in for the following methods:

web3.eth.sendTransaction()
web3.eth.call()

new web3.eth.Contract() -> myContract.methods.myMethod().call()

new web3.eth.Contract() -> myContract.methods.myMethod().send()

Property¶

String - 20 Bytes: Any ethereum address. You should have the private key for that address in your node or keystore. (Default is undefined)

Example¶


                                    web3.eth.defaultAccount;
            > undefined
                                                                                                        
            // set the default account
            web3.eth.defaultAccount = '0x11f4d0A3c12e86B4b5F39B213F7E19D048276DAe';

defaultBlock¶


                                    web3.eth.defaultBlock

The default block is used for certain methods. You can override it by passing in the defaultBlock as last parameter. The default value is "latest".

web3.eth.getBalance()
web3.eth.getCode()
web3.eth.getTransactionCount()
web3.eth.getStorageAt()
web3.eth.call()
new web3.eth.Contract() -> myContract.methods.myMethod().call()

Property¶

Default block parameters can be one of the following:

Number|BN|BigNumber: A block number
"earliest" - String: The genesis block
"latest" - String: The latest block (current head of the blockchain)
"pending" - String: The currently mined block (including pending transactions)

Default is "latest"

Example¶


                                    web3.eth.defaultBlock;
            > "latest"
                                                                                                                   
            // set the default block
            web3.eth.defaultBlock = 231;

defaultHardfork¶


                                    web3.eth.defaultHardfork

The default hardfork property can be one of the following:

"chainstart" - String
"homestead" - String
"dao" - String
"tangerineWhistle" - String
"spuriousDragon" - String
"byzantium" - String
"constantinople" - String
"petersburg" - String
"istanbul" - String
"berlin" - String
"london" - String

Default is "london"

Example¶


                                    
                                        
                                            web3.eth.defaultHardfork;
            > "london"
                                                                                                                        
            // set the default block
            web3.eth.defaultHardfork = 'istanbul';

defaultChain¶


                                    web3.eth.defaultChain

The default chain property is used for signing transactions locally.

Property¶

The default chain property can be one of the following:

"mainnet" - String
"goerli" - String
"kovan" - String
"rinkeby" - String
"ropsten" - String

Default is "mainnet"

Example¶


                                    web3.eth.defaultChain;
            > "mainnet"
                                                                                                                               
            // set the default chain
            web3.eth.defaultChain = 'goerli';

defaultCommon¶


                                    
                                        
                                            web3.eth.defaultCommon

The default common property is used for signing transactions locally.

Property¶

The default common property does contain the following Common object:

customChain - Object: The custom chain properties
- name - string: (optional) The name of the chain
- networkId - number: Network ID of the custom chain
- chainId - number: Chain ID of the custom chain
baseChain - string: (optional) mainnet, goerli, kovan, rinkeby, or ropsten
hardfork - string: (optional) chainstart, homestead, dao, tangerineWhistle, spuriousDragon, byzantium, constantinople, petersburg, istanbul, berlin, or london

Default is undefined.

Example¶


                                    
                                        
                                            web3.eth.defaultCommon;
            > {customChain: {name: 'custom-network', chainId: 1, networkId: 1}, baseChain: 'mainnet', hardfork: 'petersburg'}
                                                                                                                                           
            // set the default common
            web3.eth.defaultCommon = {customChain: {name: 'custom-network', chainId: 1, networkId: 1}, baseChain: 'mainnet', hardfork: 'petersburg'};

transactionBlockTimeout¶


                                    web3.eth.transactionBlockTimeout

The transactionBlockTimeout is used over socket-based connections. This option defines the amount of new blocks it should wait until the first confirmation happens, otherwise the PromiEvent rejects with a timeout error.

Returns¶

number: The current value of transactionBlockTimeout (default: 50)

Example¶


                                    web3.eth.transactionBlockTimeout;
            > 50
                                                                                                                
            // set the transaction block timeout
            web3.eth.transactionBlockTimeout = 100;

transactionConfirmationBlocks¶


                                    
                                        
                                            web3.eth.transactionConfirmationBlocks

This defines the number of blocks it requires until a transaction is considered confirmed.

Returns¶

number: The current value of transactionConfirmationBlocks (default: 24)

Example¶


                                    web3.eth.transactionConfirmationBlocks;
            > 24
                                                                                                               
            // set the transaction confirmations blocks
            web3.eth.transactionConfirmationBlocks = 50;

transactionPollingTimeout¶


                                    
                                        
                                            web3.eth.transactionPollingTimeout

The transactionPollingTimeout is used over HTTP connections. This option defines the number of seconds Web3 will wait for a receipt which confirms that a transaction was mined by the network. Note: If this method times out, the transaction may still be pending.

Returns¶

number: The current value of transactionPollingTimeout (default: 750)

Example¶


                                    
                                        
                                            web3.eth.transactionPollingTimeout;
            > 750
                                                                                                               
            // set the transaction polling timeout
            web3.eth.transactionPollingTimeout = 1000;

handleRevert¶


                                    web3.eth.handleRevert

The handleRevert options property defaults to false and returns the revert reason string if enabled for the following methods:

Note

The revert reason string and signature exist as a property on the returned error.

Returns¶

boolean: The current value of handleRevert (default: false)

Example¶


                                    
                                        
                                            web3.eth.handlRevert;
            > false
                                                                                                  
            // turn revert handling on
            web3.eth.handleRevert = true;

maxListenersWarningThreshold¶


                                    
                                        
                                            web3.eth.maxListenersWarningThreshold

This defines the threshold above which a warning about the number of event listeners attached to a provider which supports sockets subscriptions will be written to the console. You may see this warning if you call setProvider on large numbers of Web3 contract objects.

Returns¶

number: The current value of maxListenersWarningThreshold (default: 100)

Example¶


                                    
                                        
                                            web3.eth.maxListenersWarningThreshold;
            > 100
                                                                                                                
            // set the max listeners warning threshold
            web3.eth.maxListenersWarningThreshold = 200;

getProtocolVersion¶


                                    
                                        
                                            web3.eth.getProtocolVersion([callback])

Returns¶

Promise returns String: the protocol version.

Example¶


                                    
                                        
                                            web3.eth.getProtocolVersion()
            .then(console.log);
            > "63"

isSyncing¶


                                    
                                        
                                            web3.eth.isSyncing([callback])

Checks if the node is currently syncing and returns either a syncing object, or false.

Returns¶

Promise returns Object|Boolean - A sync object when the node is currently syncing or false:

startingBlock - Number: The block number where the sync started.

currentBlock - Number: The block number where the node is currently synced to.

highestBlock - Number: The estimated block number to sync to.

knownStates - Number: The number of estimated states to download.

pulledStates - Number: The number of already downloaded states.

Example¶


                                    
                                        
                                            web3.eth.isSyncing()
            .then(console.log);
                                                                                                            
            > {
                startingBlock: 100,
                currentBlock: 312,
                highestBlock: 512,
                knownStates: 234566,
                pulledStates: 123455
            }

getCoinbase¶


                                    
                                        
                                            getCoinbase([callback])

Returns the coinbase address to which mining rewards will go.

Returns¶

Promise returns String - bytes 20: The coinbase address set in the node for mining rewards.

Example¶


                                    
                                        
                                            web3.eth.getCoinbase()
                                                                                                                    .then(console.log);
                                                                                                                    > "0x11f4d0A3c12e86B4b5F39B213F7E19D048276DAe"

isMining¶


                                    
                                        
                                            web3.eth.isMining([callback])

Checks whether the node is mining or not.

Returns¶

Promise returns Boolean: true if the node is mining, otherwise false.

Example¶


                                    
                                        
                                            web3.eth.isMining()
                                                                                                                    .then(console.log);
                                                                                                                    > true

getHashrate¶


                                    
                                        
                                            web3.eth.getHashrate([callback])

Returns the number of hashes per second that the node is mining with.

Returns¶

Promise returns Number: Number of hashes per second.

Example¶


                                    
                                        
                                            web3.eth.getHashrate()
                                                                                                                    .then(console.log);
                                                                                                                    > 493736

getGasPrice¶


                                    
                                        
                                            web3.eth.getGasPrice([callback])

Returns the current gas price oracle. The gas price is determined by the last few blocks median gas price.

Returns¶

Promise returns String - Number string of the current gas price in wei.

See the A note on dealing with big numbers in JavaScript.

Example¶


                                    
                                        
                                            web3.eth.getGasPrice()
                                                                                                                        .then(console.log);
                                                                                                                        > "20000000000"

getFeeHistory¶


                                    
                                        
                                            web3.eth.getFeeHistory(blockCount, newestBlock, rewardPercentiles, [callback])

Transaction fee history Returns base fee per gas and transaction effective priority fee per gas history for the requested block range if available. The range between headBlock-4 and headBlock is guaranteed to be available while retrieving data from the pending block and older history are optional to support. For pre-EIP-1559 blocks the gas prices are returned as rewards and zeroes are returned for the base fee per gas.

Parameters¶

String|Number|BN|BigNumber - Number of blocks in the requested range. Between 1 and 1024 blocks can be requested in a single query. Less than requested may be returned if not all blocks are available.
String|Number|BN|BigNumber - Highest number block of the requested range.
Array of numbers - A monotonically increasing list of percentile values to sample from each block’s effective priority fees per gas in ascending order, weighted by gas used. Example: [“0”, “25”, “50”, “75”, “100”] or [“0”, “0.5”, “1”, “1.5”, “3”, “80”]
Function - (optional) Optional callback, returns an error object as first parameter and the result as second.

Returns¶

Promise returns Object - Fee history for the returned block range. The object:

Number oldestBlock - Lowest number block of the returned range.
Array of strings baseFeePerGas - An array of block base fees per gas. This includes the next block after the newest of the returned range, because this value can be derived from the newest block. Zeroes are returned for pre-EIP-1559 blocks.
Array of numbers gasUsedRatio - An array of block gas used ratios. These are calculated as the ratio of gasUsed and gasLimit.
Array of string arrays reward - An array of effective priority fee per gas data points from a single block. All zeroes are returned if the block is empty.

getAccounts¶


                                    
                                        
                                            web3.eth.getAccounts([callback])

Returns¶

Promise returns Array - An array of addresses controlled by node.

Example¶


                                    
                                        
                                            web3.eth.getAccounts()
                                                                                                                    .then(console.log);
                                                                                                                    > ["0x11f4d0A3c12e86B4b5F39B213F7E19D048276DAe", "0xDCc6960376d6C6dEa93647383FfB245CfCed97Cf"]

getBlockNumber¶


                                    
                                        
                                            web3.eth.getBlockNumber([callback])

Returns the current block number.

Returns¶

Promise returns Number - The number of the most recent block.

Example¶


                                    
                                        
                                            web3.eth.getBlockNumber()
                                                                                                                    .then(console.log);
                                                                                                                    > 2744

getBalance¶


                                    
                                        
                                            web3.eth.getBalance(address [, defaultBlock] [, callback])

Get the balance of an address at a given block.

Returns¶

Promise returns String - The current balance for the given address in wei.

See the A note on dealing with big numbers in JavaScript.

Example¶


                                    
                                        
                                            web3.eth.getBalance("0x407d73d8a49eeb85d32cf465507dd71d507100c1")
                                                                                                                    .then(console.log);
                                                                                                                    > "1000000000000"

getStorageAt¶


                                    
                                        
                                            web3.eth.getStorageAt(address, position [, defaultBlock] [, callback])

Get the storage at a specific position of an address.

Parameters¶

String - The address to get the storage from.
Number|String|BN|BigNumber - The index position of the storage.
Number|String|BN|BigNumber - (optional) If you pass this parameter it will not use the default block set with web3.eth.defaultBlock. Pre-defined block numbers as "earliest", "latest" and "pending" can also be used.
Function - (optional) Optional callback, returns an error object as first parameter and the result as second.

Returns¶

Promise returns String - The value in storage at the given position.

Example¶


                                    
                                        
                                            web3.eth.getStorageAt("0x407d73d8a49eeb85d32cf465507dd71d507100c1", 0)
                                                                                                                        .then(console.log);
                                                                                                                        > "0x033456732123ffff2342342dd12342434324234234fd234fd23fd4f23d4234"

getCode¶


                                    
                                        
                                            web3.eth.getCode(address [, defaultBlock] [, callback])

Get the code at a specific address.

Parameters¶

String - The address to get the code from.
Number|String|BN|BigNumber - (optional) If you pass this parameter it will not use the default block set with web3.eth.defaultBlock. Pre-defined block numbers as "earliest", "latest" and "pending" can also be used.
Function - (optional) Optional callback, returns an error object as first parameter and the result as second.

Returns¶

Promise returns String - The data at given address address.

Example¶


                                    
                                        
                                            web3.eth.getCode("0xd5677cf67b5aa051bb40496e68ad359eb97cfbf8")
                                                                                                                        .then(console.log);
            > "0x600160008035811a818181146012578301005b601b6001356025565b8060005260206000f25b600060078202905091905056"

getBlock¶


                                    
                                        
                                            web3.eth.getBlock(blockHashOrBlockNumber [, returnTransactionObjects] [, callback])

Returns a block matching the block number or block hash.

Parameters¶

String|Number|BN|BigNumber - The block number or block hash. Or the string "earliest", "latest" or "pending" as in the default block parameter.
Boolean - (optional, default false) If specified true, the returned block will contain all transactions as objects. If false it will only contains the transaction hashes.
Function - (optional) Optional callback, returns an error object as first parameter and the result as second.

Returns¶

Promise returns Object - The block object:

number - Number: The block number. null if a pending block.

hash 32 Bytes - String: Hash of the block. null if a pending block.

parentHash 32 Bytes - String: Hash of the parent block.

nonce 8 Bytes - String: Hash of the generated proof-of-work. null if a pending block.

sha3Uncles 32 Bytes - String: SHA3 of the uncles data in the block.

logsBloom 256 Bytes - String: The bloom filter for the logs of the block. null if a pending block.

transactionsRoot 32 Bytes - String: The root of the transaction trie of the block.

stateRoot 32 Bytes - String: The root of the final state trie of the block.

miner - String: The address of the beneficiary to whom the mining rewards were given.

difficulty - String: Integer of the difficulty for this block.

totalDifficulty - String: Integer of the total difficulty of the chain until this block.

extraData - String: The “extra data” field of this block.

size - Number: Integer the size of this block in bytes.

gasLimit - Number: The maximum gas allowed in this block.

gasUsed - Number: The total used gas by all transactions in this block.

timestamp - Number: The unix timestamp for when the block was collated.

transactions - Array: Array of transaction objects, or 32 Bytes transaction hashes depending on the returnTransactionObjects parameter.

uncles - Array: Array of uncle hashes.

Example¶


            
            
            web3.eth.getBlock(3150)
            .then(console.log);
                                                                                                                       
            > {
                "number": 3,
                 "hash": "0xef95f2f1ed3ca60b048b4bf67cde2195961e0bba6f70bcbea9a2c4e133e34b46",
                 "parentHash": "0x2302e1c0b972d00932deb5dab9eb2982f570597d9d42504c05d9c2147eaf9c88",
                 "nonce": "0xfb6e1a62d119228b",
                 "sha3Uncles": "0x1dcc4de8dec75d7aab85b567b6ccd41ad312451b948a7413f0a142fd40d49347",
                 "logsBloom": "0x00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000",
                 "transactionsRoot": "0x3a1b03875115b79539e5bd33fb00d8f7b7cd61929d5a3c574f507b8acf415bee",
                 "stateRoot": "0xf1133199d44695dfa8fd1bcfe424d82854b5cebef75bddd7e40ea94cda515bcb",
                 "miner": "0x8888f1f195afa192cfee860698584c030f4c9db1",
                 "difficulty": '21345678965432',
                 "totalDifficulty": '324567845321',
                 "size": 616,
                 "extraData": "0x",
                 "gasLimit": 3141592,
                 "gasUsed": 21662,
                 "timestamp": 1429287689,
                 "transactions": [
                 "0x9fc76417374aa880d4449a1f7f31ec597f00b1f6f3dd2d66f4c9c6c445836d8b"
                 ],
                 "uncles": []
            }

getBlockTransactionCount¶


            
            
            web3.eth.getBlockTransactionCount(blockHashOrBlockNumber [, callback])

Returns the number of transaction in a given block.

Parameters¶

String|Number|BN|BigNumber - The block number or hash. Or the string "earliest", "latest" or "pending" as in the default block parameter.
Function - (optional) Optional callback, returns an error object as first parameter and the result as second.

Returns¶

Promise returns Number - The number of transactions in the given block.

Example¶


            
            
            web3.eth.getBlockTransactionCount("0x407d73d8a49eeb85d32cf465507dd71d507100c1")
            .then(console.log);
            > 1

getBlockUncleCount¶


            
            
            web3.eth.getBlockUncleCount(blockHashOrBlockNumber [, callback])

Returns the number of uncles in a block from a block matching the given block hash.

Parameters¶

String|Number|BN|BigNumber - The block number or hash. Or the string "earliest", "latest" or "pending" as in the default block parameter.
Function - (optional) Optional callback, returns an error object as first parameter and the result as second.

Returns¶

Promise returns Number - The number of transactions in the given block.

Example¶


            
            
            web3.eth.getBlockUncleCount("0x407d73d8a49eeb85d32cf465507dd71d507100c1")
            .then(console.log);
            > 1

getUncle¶


            
            
            web3.eth.getUncle(blockHashOrBlockNumber, uncleIndex [, returnTransactionObjects] [, callback])

Returns a blocks uncle by a given uncle index position.

Parameters¶

String|Number|BN|BigNumber - The block number or hash. Or the string "earliest", "latest" or "pending" as in the default block parameter.
Number - The index position of the uncle.
Boolean - (optional, default false) If specified true, the returned block will contain all transactions as objects. By default it is false so, there is no need to explictly specify false. And, if false it will only contains the transaction hashes.
Function - (optional) Optional callback, returns an error object as first parameter and the result as second.

Returns¶

Promise returns Object - the returned uncle. For a return value see web3.eth.getBlock().

Note

An uncle doesn’t contain individual transactions.

Example¶


            
            
            web3.eth.getUncle(500, 0)
            .then(console.log);
            > // see web3.eth.getBlock

getTransaction¶


            
            
            web3.eth.getTransaction(transactionHash [, callback])

Returns a transaction matching the given transaction hash.

Parameters¶

String - The transaction hash.
Function - (optional) Optional callback, returns an error object as first parameter and the result as second.

Returns¶

Promise returns Object - A transaction object its hash transactionHash:

hash 32 Bytes - String: Hash of the transaction.

nonce - Number: The number of transactions made by the sender prior to this one.

blockHash 32 Bytes - String: Hash of the block where this transaction was in. null if pending.

blockNumber - Number: Block number where this transaction was in. null if pending.

transactionIndex - Number: Integer of the transactions index position in the block. null if pending.

from - String: Address of the sender.

to - String: Address of the receiver. null if it’s a contract creation transaction.

value - String: Value transferred in wei.

gasPrice - String: Gas price provided by the sender in wei.

gas - Number: Gas provided by the sender.

input - String: The data sent along with the transaction.

Example¶


            
            
            web3.eth.getTransaction('0x9fc76417374aa880d4449a1f7f31ec597f00b1f6f3dd2d66f4c9c6c445836d8b§234')
            .then(console.log);
                                                                                                                      
            > {
                 "hash": "0x9fc76417374aa880d4449a1f7f31ec597f00b1f6f3dd2d66f4c9c6c445836d8b",
                 "nonce": 2,
                 "blockHash": "0xef95f2f1ed3ca60b048b4bf67cde2195961e0bba6f70bcbea9a2c4e133e34b46",
                 "blockNumber": 3,
                 "transactionIndex": 0,
                 "from": "0xa94f5374fce5edbc8e2a8697c15331677e6ebf0b",
                 "to": "0x6295ee1b4f6dd65047762f924ecd367c17eabf8f",
                 "value": '123450000000000000',
                 "gas": 314159,
                 "gasPrice": '2000000000000',
                 "input": "0x57cb2fc4"
            }

getPendingTransactions¶


            
            
            web3.eth.getPendingTransactions([, callback])

Returns a list of pending transactions.

Parameters¶

Function - (optional) Optional callback, returns an error object as first parameter and the result as second.

Returns¶

Promise<object[]> - Array of pending transactions:

hash 32 Bytes - String: Hash of the transaction.

nonce - Number: The number of transactions made by the sender prior to this one.

blockHash 32 Bytes - String: Hash of the block where this transaction was in. null if pending.

blockNumber - Number: Block number where this transaction was in. null if pending.

transactionIndex - Number: Integer of the transactions index position in the block. null if pending.

from - String: Address of the sender.

to - String: Address of the receiver. null when it’s a contract creation transaction.

value - String: Value transferred in wei.

gasPrice - String: The wei per unit of gas provided by the sender in wei.

gas - Number: Gas provided by the sender.

input - String: The data sent along with the transaction.

Example¶


            
            
             web3.eth.getPendingTransactions().then(console.log);
            >  [
                 {
                         hash: '0x9fc76417374aa880d4449a1f7f31ec597f00b1f6f3dd2d66f4c9c6c445836d8b',
                         nonce: 2,
                         blockHash: '0xef95f2f1ed3ca60b048b4bf67cde2195961e0bba6f70bcbea9a2c4e133e34b46',
                         blockNumber: 3,
                         transactionIndex: 0,
                         from: '0xa94f5374fce5edbc8e2a8697c15331677e6ebf0b',
                         to: '0x6295ee1b4f6dd65047762f924ecd367c17eabf8f',
                         value: '123450000000000000',
                         gas: 314159,
                         gasPrice: '2000000000000',
                         input: '0x57cb2fc4'
                         v: '0x3d',
                         r: '0xaabc9ddafffb2ae0bac4107697547d22d9383667d9e97f5409dd6881ce08f13f',
                         s: '0x69e43116be8f842dcd4a0b2f760043737a59534430b762317db21d9ac8c5034'
                 },....,{
                         hash: '0x9fc76417374aa880d4449a1f7f31ec597f00b1f6f3dd2d66f4c9c6c445836d8b',
                         nonce: 3,
                         blockHash: '0xef95f2f1ed3ca60b048b4bf67cde2195961e0bba6f70bcbea9a2c4e133e34b46',
                         blockNumber: 4,
                         transactionIndex: 0,
                         from: '0xa94f5374fce5edbc8e2a8697c15331677e6ebf0b',
                         to: '0x6295ee1b4f6dd65047762f924ecd367c17eabf8f',
                         value: '123450000000000000',
                         gas: 314159,
                         gasPrice: '2000000000000',
                         input: '0x57cb2fc4'
                         v: '0x3d',
                         r: '0xaabc9ddafffb2ae0bac4107697547d22d9383667d9e97f5409dd6881ce08f13f',
                         s: '0x69e43116be8f842dcd4a0b2f760043737a59534430b762317db21d9ac8c5034'
                 }
            ]

getTransactionFromBlock¶


            
            
            getTransactionFromBlock(hashStringOrNumber, indexNumber [, callback])

Returns a transaction based on a block hash or number and the transaction’s index position.

Parameters¶

String|Number|BN|BigNumber - A block number or hash. Or the string "earliest", "latest" or "pending" as in the default block parameter.
Number - The transaction’s index position.
Function - (optional) Optional callback, returns an error object as first parameter and the result as second.

Returns¶

Promise returns Object - A transaction object, see web3.eth.getTransaction:

Example¶


            
            
            var transaction = web3.eth.getTransactionFromBlock('0x4534534534', 2)
            .then(console.log);
            > // see web3.eth.getTransaction

getTransactionReceipt¶


            
            
            web3.eth.getTransactionReceipt(hash [, callback])

Returns the receipt of a transaction by transaction hash.

Note

The receipt is not available for pending transactions and returns null.

Parameters¶

String - The transaction hash.
Function - (optional) Optional callback, returns an error object as first parameter and the result as second.

Returns¶

Promise returns Object - A transaction receipt object, or null if no receipt was found:

status - Boolean: TRUE if the transaction was successful, FALSE if the EVM reverted the transaction.

blockHash 32 Bytes - String: Hash of the block where this transaction was in.

blockNumber - Number: Block number where this transaction was in.

transactionHash 32 Bytes - String: Hash of the transaction.

transactionIndex- Number: Integer of the transactions index position in the block.

from - String: Address of the sender.

to - String: Address of the receiver. null when it’s a contract creation transaction.

contractAddress - String: The contract address created, if the transaction was a contract creation, otherwise null.

cumulativeGasUsed - Number: The total amount of gas used when this transaction was executed in the block.

gasUsed- Number: The amount of gas used by this specific transaction alone.

logs - Array: Array of log objects, which this transaction generated.

Example¶


            
            
            var receipt = web3.eth.getTransactionReceipt('0x9fc76417374aa880d4449a1f7f31ec597f00b1f6f3dd2d66f4c9c6c445836d8b')
            .then(console.log);
                                                                                                                            
            > {
                    "status": true,
                    "transactionHash": "0x9fc76417374aa880d4449a1f7f31ec597f00b1f6f3dd2d66f4c9c6c445836d8b",
                    "transactionIndex": 0,
                    "blockHash": "0xef95f2f1ed3ca60b048b4bf67cde2195961e0bba6f70bcbea9a2c4e133e34b46",
                    "blockNumber": 3,
                    "contractAddress": "0x11f4d0A3c12e86B4b5F39B213F7E19D048276DAe",
                    "cumulativeGasUsed": 314159,
                    "gasUsed": 30234,
                    "logs": [{
                         // logs as returned by getPastLogs, etc.
                    }, ...]
            }

getTransactionCount¶


            
            
            
web3.eth.getTransactionCount(address [, defaultBlock] [, callback])

Get the number of transactions sent from this address.

Parameters¶

String - The address to get the numbers of transactions from.
Number|String|BN|BigNumber - (optional) If you pass this parameter it will not use the default block set with web3.eth.defaultBlock. Pre-defined block numbers as "earliest", "latest" and "pending" can also be used.
Function - (optional) Optional callback, returns an error object as first parameter and the result as second.

Returns¶

Promise returns Number - The number of transactions sent from the given address.

Example¶


            
            
            web3.eth.getTransactionCount("0x11f4d0A3c12e86B4b5F39B213F7E19D048276DAe")
            .then(console.log);
            > 1

sendTransaction¶


            
            
            web3.eth.sendTransaction(transactionObject [, callback])

Sends a transaction to the network.

Parameters¶

Object - The transaction object to send:
- from - String|Number: The address for the sending account. Uses the web3.eth.defaultAccount property, if not specified. Or an address or index of a local wallet in web3.eth.accounts.wallet.
- to - String: (optional) The destination address of the message, left undefined for a contract-creation transaction.
- value - Number|String|BN|BigNumber: (optional) The value transferred for the transaction in wei, also the endowment if it’s a contract-creation transaction.
- gas - Number: (optional, default: To-Be-Determined) The amount of gas to use for the transaction (unused gas is refunded).
- gasPrice - Number|String|BN|BigNumber: (optional) The price of gas for this transaction in wei, defaults to web3.eth.gasPrice.
- type - Number|String|BN|BigNumber: (optional) A positive unsigned 8-bit number between 0 and 0x7f that represents the type of the transaction.
- maxFeePerGas - Number|String|BN: (optional, defaulted to (2 * block.baseFeePerGas) + maxPriorityFeePerGas) The maximum fee per gas that the transaction is willing to pay in total
- maxPriorityFeePerGas - Number|String|BN (optional, defaulted to 1 Gwei) The maximum fee per gas to give miners to incentivize them to include the transaction (Priority fee)
- accessList - List of hexstrings (optional) a list of addresses and storage keys that the transaction plans to access
- data - String: (optional) Either a ABI byte string containing the data of the function call on a contract, or in the case of a contract-creation transaction the initialisation code.
- nonce - Number: (optional) Integer of the nonce. This allows to overwrite your own pending transactions that use the same nonce.
- chain - String: (optional) Defaults to mainnet.
- hardfork - String: (optional) Defaults to london.
- common - Object: (optional) The common object
  
  customChain - Object: The custom chain properties
  
  name - string: (optional) The name of the chain
  
  networkId - number: Network ID of the custom chain
  
  chainId - number: Chain ID of the custom chain
  
  baseChain - string: (optional) mainnet, goerli, kovan, rinkeby, or ropsten
  
  hardfork - string: (optional) chainstart, homestead, dao, tangerineWhistle, spuriousDragon, byzantium, constantinople, petersburg, istanbul, berlin, or london
callback - Function: (optional) Optional callback, returns an error object as first parameter and the result as second.

Note

The from property can also be an address or index from the web3.eth.accounts.wallet. It will then sign locally using the private key of that account, and send the transaction via web3.eth.sendSignedTransaction(). If the properties chain and hardfork or common are not set, Web3 will try to set appropriate values by querying the network for its chainId and networkId.

Returns¶

The callback will return the 32 bytes transaction hash.

PromiEvent: A promise combined event emitter. Resolves when the transaction receipt is available. The following events are also available:

sending returns payload: Object: Fired immediately before transmitting the transaction request.
sent returns payload: Object: Fired immediately after the request body has been written to the client, but before the transaction hash is received.
"transactionHash" returns transactionHash: String: Fired when the transaction hash is available.
"receipt" returns receipt: Object: Fired when the transaction receipt is available.
"confirmation" returns confirmationNumber: Number, receipt: Object, latestBlockHash: String: Fired for every confirmation up to the 12th confirmation. Receives the confirmation number as the first and the receipt as the second argument. Fired from confirmation 0 on, which is the block where it’s mined.

"error" returns error: Error: Fired if an error occurs during sending. If the transaction was rejected by the network with a receipt, the receipt will be available as a property on the error object.

Example¶


            
            
            // compiled solidity source code using https://remix.ethereum.org
            var code = "603d80600c6000396000f3007c01000000000000000000000000000000000000000000000000000000006000350463c6888fa18114602d57005b6007600435028060005260206000f3";
                                                                                                            
                                                                                                                       
            // using the callback
            web3.eth.sendTransaction({
                 from: '0xde0B295669a9FD93d5F28D9Ec85E40f4cb697BAe',
                 data: code // deploying a contract
            }, function(error, hash){
                 ...
            });
                                                                                                                       
            // using the promise
            web3.eth.sendTransaction({
                 from: '0xde0B295669a9FD93d5F28D9Ec85E40f4cb697BAe',
                 to: '0x11f4d0A3c12e86B4b5F39B213F7E19D048276DAe',
                 value: '1000000000000000'
            })
            .then(function(receipt){
                 ...
            });
                                                                                                                        
                                                                                                                        
            // using the event emitter
            web3.eth.sendTransaction({
                 from: '0xde0B295669a9FD93d5F28D9Ec85E40f4cb697BAe',
                 to: '0x11f4d0A3c12e86B4b5F39B213F7E19D048276DAe',
                 value: '1000000000000000'
            })
            .on('transactionHash', function(hash){
                 ...
            })
            .on('receipt', function(receipt){
                 ...
            })
            .on('confirmation', function(confirmationNumber, receipt){ ... })
            .on('error', console.error); // If a out of gas error, the second parameter is the receipt.

sendSignedTransaction¶


            
            
            web3.eth.sendSignedTransaction(signedTransactionData [, callback])

Sends an already signed transaction, generated for example using web3.eth.accounts.signTransaction.

Parameters¶

String - Signed transaction data in HEX format
Function - (optional) Optional callback, returns an error object as first parameter and the result as second.

Returns¶

PromiEvent: A promise combined event emitter. Resolves when the transaction receipt is available.

Please see the return values for web3.eth.sendTransaction for details.

Example¶


            
            
            var Tx = require('@ethereumjs/tx').Transaction;
            var privateKey = Buffer.from('e331b6d69882b4cb4ea581d88e0b604039a3de5967688d3dcffdd2270c0fd109', 'hex');
                                                                                                                        
            var rawTx = {
                 nonce: '0x00',
                 gasPrice: '0x09184e72a000',
                 gasLimit: '0x2710',
                 to: '0x0000000000000000000000000000000000000000',
                 value: '0x00',
                 data: '0x7f7465737432000000000000000000000000000000000000000000000000000000600057'
            }
                                                                                                                        
            var tx = new Tx(rawTx, {'chain':'ropsten'});
            tx.sign(privateKey);
                                                                                                               
            var serializedTx = tx.serialize();
                                                                                                                        
            // console.log(serializedTx.toString('hex'));
            // 0xf889808609184e72a00082271094000000000000000000000000000000000000000080a47f74657374320000000000000000000000000000000000000000000000000000006000571ca08a8bbf888cfa37bbf0bb965423625641fc956967b81d12e23709cead01446075a01ce999b56a8a88504be365442ea61239198e23d1fce7d00fcfc5cd3b44b7215f
                                                                                                                        
            web3.eth.sendSignedTransaction('0x' + serializedTx.toString('hex'))
            .on('receipt', console.log);
                                                                                                                        
            > // see eth.getTransactionReceipt() for details

Note

When using ethereumjs-tx@2.0.0 if you don’t specify the parameter chain it will use mainnet by default.

sign¶


            
            
            web3.eth.sign(dataToSign, address [, callback])

Signs data using a specific account. This account needs to be unlocked.

Parameters¶

String - Data to sign. If it is a string it will be converted using web3.utils.utf8ToHex.
String|Number - Address to sign data with. Can be an address or the index of a local wallet in web3.eth.accounts.wallet.
Function - (optional) Optional callback, returns an error object as first parameter and the result as second.

Returns¶

Promise returns String - The signature.

Example¶


             
             
             web3.eth.sign("Hello world", "0x11f4d0A3c12e86B4b5F39B213F7E19D048276DAe")
             .then(console.log);
             > "0x30755ed65396facf86c53e6217c52b4daebe72aa4941d89635409de4c9c7f9466d4e9aaec7977f05e923889b33c0d0dd27d7226b6e6f56ce737465c5cfd04be400"
                                                                                                                        
             // the below is the same
             web3.eth.sign(web3.utils.utf8ToHex("Hello world"), "0x11f4d0A3c12e86B4b5F39B213F7E19D048276DAe")
             .then(console.log);
             > "0x30755ed65396facf86c53e6217c52b4daebe72aa4941d89635409de4c9c7f9466d4e9aaec7977f05e923889b33c0d0dd27d7226b6e6f56ce737465c5cfd04be400"

signTransaction¶


             
             
             web3.eth.signTransaction(transactionObject, address [, callback])

Signs a transaction. This account needs to be unlocked.

Parameters¶

Object - The transaction data to sign. See web3.eth.sendTransaction() for more.
String - Address to sign transaction with.
Function - (optional) Optional callback, returns an error object as first parameter and the result as second.

Returns¶

Promise returns Object - The RLP encoded transaction. The raw property can be used to send the transaction using web3.eth.sendSignedTransaction.

Example¶


             
             
             web3.eth.signTransaction({
                from: "0xEB014f8c8B418Db6b45774c326A0E64C78914dC0",
                gasPrice: "20000000000",
                gas: "21000",
                to: '0x3535353535353535353535353535353535353535',
                value: "1000000000000000000",
                data: ""
             }).then(console.log);
             > {
                raw: '0xf86c808504a817c800825208943535353535353535353535353535353535353535880de0b6b3a76400008025a04f4c17305743700648bc4f6cd3038ec6f6af0df73e31757007b7f59df7bee88da07e1941b264348e80c78c4027afc65a87b0a5e43e86742b8ca0823584c6788fd0',
                tx: {
                     nonce: '0x0',
                     gasPrice: '0x4a817c800',
                     gas: '0x5208',
                     to: '0x3535353535353535353535353535353535353535',
                     value: '0xde0b6b3a7640000',
                     input: '0x',
                     v: '0x25',
                     r: '0x4f4c17305743700648bc4f6cd3038ec6f6af0df73e31757007b7f59df7bee88d',
                     s: '0x7e1941b264348e80c78c4027afc65a87b0a5e43e86742b8ca0823584c6788fd0',
                     hash: '0xda3be87732110de6c1354c83770aae630ede9ac308d9f7b399ecfba23d923384'
                }
             }

call¶


             
             
             web3.eth.call(callObject [, defaultBlock] [, callback])

Executes a message call transaction, which is directly executed in the VM of the node, but never mined into the blockchain.

Parameters¶

Object - A transaction object, see web3.eth.sendTransaction. For calls the from property is optional however it is highly recommended to explicitly set it or it may default to address(0) depending on your node or provider.
Number|String|BN|BigNumber - (optional) If you pass this parameter it will not use the default block set with web3.eth.defaultBlock. Pre-defined block numbers as "earliest", "latest" and "pending" can also be used.
Function - (optional) Optional callback, returns an error object as first parameter and the result as second.

Returns¶

Promise returns String: The returned data of the call, e.g. a smart contract functions return value.

Example¶


             
             
             web3.eth.call({
                    to: "0x11f4d0A3c12e86B4b5F39B213F7E19D048276DAe", // contract address
                    data: "0xc6888fa10000000000000000000000000000000000000000000000000000000000000003"
             })
             .then(console.log);
             > "0x000000000000000000000000000000000000000000000000000000000000000a"

estimateGas¶


             
             
             web3.eth.estimateGas(callObject [, callback])

Executes a message call or transaction and returns the amount of the gas used. Note: You must specify a from address otherwise you may experience odd behavior.

Parameters¶

Object - A transaction object, see web3.eth.sendTransaction with the difference that for calls the from property is optional as well.
Function - (optional) Optional callback, returns an error object as first parameter and the result as second.

Returns¶

Promise returns Number - the used gas for the simulated call/transaction.

Example¶


             
             
             web3.eth.estimateGas({
                    to: "0x11f4d0A3c12e86B4b5F39B213F7E19D048276DAe",
                    data: "0xc6888fa10000000000000000000000000000000000000000000000000000000000000003"
             })
             .then(console.log);
             > "0x0000000000000000000000000000000000000000000000000000000000000015"

getPastLogs¶


             
             
             web3.eth.getPastLogs(options [, callback])

Gets past logs, matching the given options.

Parameters¶

Object - The filter options as follows:

fromBlock - Number|String: The number of the earliest block ("latest" may be given to mean the most recent and "pending" currently mining, block). By default "latest".

toBlock - Number|String: The number of the latest block ("latest" may be given to mean the most recent and "pending" currently mining, block). By default "latest".

address - String|Array: An address or a list of addresses to only get logs from particular account(s).

topics - Array: An array of values which must each appear in the log entries. The order is important, if you want to leave topics out use null, e.g. [null, '0x12...']. You can also pass an array for each topic with options for that topic e.g. [null, ['option1', 'option2']]

Returns¶

Promise returns Array - Array of log objects.

The structure of the returned event Object in the Array looks as follows:

address - String: From which this event originated from.
data - String: The data containing non-indexed log parameter.
topics - Array: An array with max 4 32 Byte topics, topic 1-3 contains indexed parameters of the log.
logIndex - Number: Integer of the event index position in the block.
transactionIndex - Number: Integer of the transaction’s index position, the event was created in.
transactionHash 32 Bytes - String: Hash of the transaction this event was created in.
blockHash 32 Bytes - String: Hash of the block where this event was created in. null if still pending.
blockNumber - Number: The block number where this log was created in. null if still pending.

Example¶


             
             
             web3.eth.getPastLogs({
                 address: "0x11f4d0A3c12e86B4b5F39B213F7E19D048276DAe",
                 topics: ["0x033456732123ffff2342342dd12342434324234234fd234fd23fd4f23d4234"]
             })
             .then(console.log);
                                                                                                                   
             > [{
                 data: '0x7f9fade1c0d57a7af66ab4ead79fade1c0d57a7af66ab4ead7c2c2eb7b11a91385',
                 topics: ['0xfd43ade1c09fade1c0d57a7af66ab4ead7c2c2eb7b11a91ffdd57a7af66ab4ead7', '0x7f9fade1c0d57a7af66ab4ead79fade1c0d57a7af66ab4ead7c2c2eb7b11a91385']
                 logIndex: 0,
                 transactionIndex: 0,
                 transactionHash: '0x7f9fade1c0d57a7af66ab4ead79fade1c0d57a7af66ab4ead7c2c2eb7b11a91385',
                 blockHash: '0xfd43ade1c09fade1c0d57a7af66ab4ead7c2c2eb7b11a91ffdd57a7af66ab4ead7',
                 blockNumber: 1234,
                 address: '0xde0B295669a9FD93d5F28D9Ec85E40f4cb697BAe'
             },{...}]

getWork¶


             
             
             web3.eth.getWork([callback])

Gets work for miners to mine on. Returns the hash of the current block, the seedHash, and the boundary condition to be met (“target”).

Parameters¶

Function - (optional) Optional callback, returns an error object as first parameter and the result as second.

Returns¶

Promise returns Array - the mining work with the following structure:

String 32 Bytes - at index 0: current block header pow-hash

String 32 Bytes - at index 1: the seed hash used for the DAG.

String 32 Bytes - at index 2: the boundary condition (“target”), 2^256 / difficulty.

Example¶


             
             
             web3.eth.getWork()
             .then(console.log);
             > [
                 "0x1234567890abcdef1234567890abcdef1234567890abcdef1234567890abcdef",
                 "0x5EED00000000000000000000000000005EED0000000000000000000000000000",
             "0xd1ff1c01710000000000000000000000d1ff1c01710000000000000000000000"
             ]

submitWork¶


             
             
             web3.eth.submitWork(nonce, powHash, digest, [callback])

Used for submitting a proof-of-work solution.

Parameters¶

String 8 Bytes: The nonce found (64 bits)
String 32 Bytes: The header’s pow-hash (256 bits)
String 32 Bytes: The mix digest (256 bits)
Function - (optional) Optional callback, returns an error object as first parameter and the result as second.

Returns¶

Promise returns Boolean - Returns TRUE if the provided solution is valid, otherwise FALSE.

Example¶


             
             
             web3.eth.submitWork([
                  "0x0000000000000001",
                  "0x1234567890abcdef1234567890abcdef1234567890abcdef1234567890abcdef",
                  "0xD1FE5700000000000000000000000000D1FE5700000000000000000000000000"
             ])
             .then(console.log);
             > true

requestAccounts¶


             
             
             web3.eth.requestAccounts([callback])

This method will request/enable the accounts from the current environment. This method will only work if you’re using the injected provider from a application like Metamask, Status or TrustWallet. It doesn’t work if you’re connected to a node with a default Web3.js provider (WebsocketProvider, HttpProvidder and IpcProvider).

For more information about the behavior of this method please read EIP-1102: Opt-in account exposure.

Parameters¶

Function - (optional) Optional callback, returns an error object as first parameter and the result as second.

Returns¶

Promise<Array> - Returns an array of enabled accounts.

Example¶


             
             
             web3.eth.requestAccounts().then(console.log);
             > ['0aae0B295369a9FD31d5F28D9Ec85E40f4cb692BAf', '0xde0B295669a9FD93d5F28D9Ec85E40f4cb697BAe']

getChainId¶


                                    
                                       
             web3.eth.getChainId([callback])

Returns the chain ID of the current connected node as described in the EIP-695.

Returns¶

Promise<Number> - Returns chain ID.

Example¶


                                    
                                        
             web3.eth.getChainId().then(console.log);
             > 61

getNodeInfo¶


                                    
                                        
             web3.eth.getNodeInfo([callback])

Returns¶

Promise<String> - The current client version.

Example¶


                                    
                                        
             web3.eth.getNodeInfo().then(console.log);
             > "Mist/v0.9.3/darwin/go1.4.1"

getProof¶


                                    
                                        
             web3.eth.getProof(address, storageKey, blockNumber, [callback])

Returns the account and storage-values of the specified account including the Merkle-proof as described in EIP-1186.

Parameters¶

String 20 Bytes: The Address of the account or contract.
Number[] | BigNumber[] | BN[] | String[] 32 Bytes: Array of storage-keys which should be proofed and included. See web3.eth.getStorageAt.
Number | String | BN | BigNumber: Integer block number. Pre-defined block numbers as "earliest", "latest" and "pending" can also be used.
Function - (optional) Optional callback, returns an error object as first parameter and the result as second.

Returns¶

Promise<Object> - A account object.

address - String: The address of the account.

balance - String: The balance of the account. See web3.eth.getBalance.

codeHash - String: hash of the code of the account. For a simple account without code it will return "0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470".

nonce - String: Nonce of the account.

storageHash - String: SHA3 of the StorageRoot. All storage will deliver a MerkleProof starting with this rootHash.

accountProof - String[]:Array of rlp-serialized MerkleTree-Nodes, starting with the stateRoot-Node, following the path of the SHA3 (address) as key.

storageProof - Object[] Array of storage-entries as requested.

key - String The requested storage key.

value - String The storage value.

Example¶


                                    
                                        
             web3.eth.getProof(
                 "0x1234567890123456789012345678901234567890",
                 ["0x0000000000000000000000000000000000000000000000000000000000000000","0x0000000000000000000000000000000000000000000000000000000000000001"],
                 "latest"
             ).then(console.log);
             > {
                 "address": "0x1234567890123456789012345678901234567890",
                 "accountProof": [
                     "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",
                     "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",
                     "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",
                     "0xf851808080a009833150c367df138f1538689984b8a84fc55692d3d41fe4d1e5720ff5483a6980808080808080808080a0a319c1c415b271afc0adcb664e67738d103ac168e0bc0b7bd2da7966165cb9518080"
                 ],
                 "balance": 0,
                 "codeHash": "0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470",
                 "nonce": 0,
                 "storageHash": "0x56e81f171bcc55a6ff8345e692c0f86e5b48e01b996cadc001622fb5e363b421",
                 "storageProof": [
                     {
                         "key": "0x0000000000000000000000000000000000000000000000000000000000000000",
                         "value": '0',
                         "proof": []
                     },
                     {
                         "key": "0x0000000000000000000000000000000000000000000000000000000000000001",
                         "value": '0',
                         "proof": []
                     }
                 ]
             }

Section-3

web3.eth.subscribe¶

The web3.eth.subscribe function lets you subscribe to specific events in the blockchain.

subscribe¶


                                    
                                        
             web3.eth.subscribe(type [, options] [, callback]);

Parameters¶

String - The subscription you want to subscribe to.
Mixed - (optional) Optional additional parameters, depending on the subscription type.
Function - (optional) Optional callback, returns an error object as first parameter and the result as second. Will be called for each incoming subscription, and the subscription itself as the 3rd parameter.

Returns¶

EventEmitter - A Subscription instance

subscription.id: The subscription id, used to identify and unsubscribing the subscription.

subscription.subscribe([callback]): Can be used to re-subscribe with the same parameters.

subscription.unsubscribe([callback]): Unsubscribes the subscription and returns TRUE in the callback if successful.

subscription.arguments: The subscription arguments, used when re-subscribing.

on("data") returns Object: Fires on each incoming log with the log object as argument.

on("changed") returns Object: Fires on each log which was removed from the blockchain. The log will have the additional property "removed: true".

on("error") returns Object: Fires when an error in the subscription occurs.

on("connected") returns String: Fires once after the subscription successfully connected. Returns the subscription id.

Notification returns¶

Mixed - depends on the subscription, see the different subscriptions for more.

Example¶


                                    
                                        
             var subscription = web3.eth.subscribe('logs', {
                 address: '0x123456..',
                 topics: ['0x12345...']
             }, function(error, result){
                 if (!error)
                     console.log(result);
             });
                                                                                                                       
             // unsubscribes the subscription
             subscription.unsubscribe(function(error, success){
                 if(success)
                     console.log('Successfully unsubscribed!');
             });

clearSubscriptions¶


                                        
                                            
             web3.eth.clearSubscriptions()

Resets subscriptions.

Note

This will not reset subscriptions from other packages like web3-shh, as they use their own requestManager.

Parameters¶

Boolean: If true it keeps the "syncing" subscription.

Returns¶

Boolean

Example¶


                                        
                                            
             web3.eth.subscribe('logs', {} ,function(){ ... });

             ...
                                                                                                       
             web3.eth.clearSubscriptions();

subscribe(“pendingTransactions”)¶


                                        
                                            
             web3.eth.subscribe('pendingTransactions' [, callback]);

Subscribes to incoming pending transactions.

Parameters¶

String - "pendingTransactions", the type of the subscription.
Function - (optional) Optional callback, returns an error object as first parameter and the result as second. Will be called for each incoming subscription.

Returns¶

EventEmitter: An subscription instance as an event emitter with the following events:

"data" returns String: Fires on each incoming pending transaction and returns the transaction hash.
"error" returns Object: Fires when an error in the subscription occurs.

Notification returns¶

Object|Null - First parameter is an error object if the subscription failed.
String - Second parameter is the transaction hash.

Example¶


                                        
                                            
             var subscription = web3.eth.subscribe('pendingTransactions', function(error, result){
                 if (!error)
                     console.log(result);
             })
             .on("data", function(transaction){
                 console.log(transaction);
             });
                                                                                                                                               
             // unsubscribes the subscription
             subscription.unsubscribe(function(error, success){
                 if(success)
                     console.log('Successfully unsubscribed!');
             });

subscribe(“newBlockHeaders”)¶


                                        
                                            
             web3.eth.subscribe('newBlockHeaders' [, callback]);

Subscribes to incoming block headers. This can be used as timer to check for changes on the blockchain.

Parameters¶

String - "newBlockHeaders", the type of the subscription.
Function - (optional) Optional callback, returns an error object as first parameter and the result as second. Will be called for each incoming subscription.

Returns¶

EventEmitter: An subscription instance as an event emitter with the following events:

"data" returns Object: Fires on each incoming block header.
"error" returns Object: Fires when an error in the subscription occurs.
"connected" returns Number: Fires once after the subscription successfully connected. Returns the subscription id.

The structure of a returned block header is as follows:

number - Number: The block number. null when its pending block.

hash 32 Bytes - String: Hash of the block. null when its pending block.

parentHash 32 Bytes - String: Hash of the parent block.

nonce 8 Bytes - String: Hash of the generated proof-of-work. null when its pending block.

sha3Uncles 32 Bytes - String: SHA3 of the uncles data in the block.

logsBloom 256 Bytes - String: The bloom filter for the logs of the block. null when its pending block.

transactionsRoot 32 Bytes - String: The root of the transaction trie of the block

stateRoot 32 Bytes - String: The root of the final state trie of the block.

receiptsRoot 32 Bytes - String: The root of the receipts.

miner - String: The address of the beneficiary to whom the mining rewards were given.

extraData - String: The “extra data” field of this block.

gasLimit - Number: The maximum gas allowed in this block.

gasUsed - Number: The total used gas by all transactions in this block.

timestamp - Number: The unix timestamp for when the block was collated.

Notification returns¶

Object|Null - First parameter is an error object if the subscription failed.
Object - The block header object like above.

Example¶


                                        
                                            
             var subscription = web3.eth.subscribe('newBlockHeaders', function(error, result){
                 if (!error) {
                     console.log(result);
                                                                                                                                                
                     return;
                }
                                                                                                                                      
                 console.error(error);
             })
             .on("connected", function(subscriptionId){
                 console.log(subscriptionId);
             })
             .on("data", function(blockHeader){
                 console.log(blockHeader);
             })
             .on("error", console.error);
                                                                                                                                  
             // unsubscribes the subscription
             subscription.unsubscribe(function(error, success){
                 if (success) {
                     console.log('Successfully unsubscribed!');
                 }
             });

subscribe(“syncing”)¶


                                        
                                            
             web3.eth.subscribe('syncing' [, callback]);

Subscribe to syncing events. This will return an object when the node is syncing and when it’s finished syncing will return FALSE.

Parameters¶

String - "syncing", the type of the subscription.
Function - (optional) Optional callback, returns an error object as first parameter and the result as second. Will be called for each incoming subscription.

Returns¶

EventEmitter: An subscription instance as an event emitter with the following events:

"data" returns Object: Fires on each incoming sync object as argument.
"changed" returns Object: Fires when the synchronisation is started with true and when finished with false.
"error" returns Object: Fires when an error in the subscription occurs.

For the structure of a returned event Object see web3.eth.isSyncing return values.

Notification returns¶

Object|Null - First parameter is an error object if the subscription failed.
Object|Boolean - The syncing object, when started it will return true once or when finished it will return false once.

Example¶


                                        
                                            
             var subscription = web3.eth.subscribe('syncing', function(error, sync){
                 if (!error)
                     console.log(sync);
             })
             .on("data", function(sync){
                 // show some syncing stats
             })
             .on("changed", function(isSyncing){
                 if(isSyncing) {
                     // stop app operation
                 } else {
                     // regain app operation
                 }
             });
                                                                                                                                                    
             // unsubscribes the subscription
             subscription.unsubscribe(function(error, success){
                 if(success)
                     console.log('Successfully unsubscribed!');
             });

subscribe(“logs”)¶


                                        
                                            
             web3.eth.subscribe('logs', options [, callback]);

Subscribes to incoming logs, filtered by the given options. If a valid numerical fromBlock options property is set, Web3 will retrieve logs beginning from this point, backfilling the response as necessary.

Parameters¶

"logs" - String, the type of the subscription.
Object - The subscription options

fromBlock - Number: The fromBlock dictates at which block the subscription will start from, if it is left empty, the default is latest (a.k.a the chain head)

address - String|Array: An address or a list of addresses to only get logs from particular account(s).

topics - Array: An array of values which must each appear in the log entries. The order is important, if you want to leave topics out use null, e.g. [null, '0x00...']. You can also pass another array for each topic with options for that topic e.g. [null, ['option1', 'option2']]

callback - Function: (optional) Optional callback, returns an error object as first parameter and the result as second. Will be called for each incoming subscription.

Returns¶

EventEmitter: A subscription instance as an event emitter with the following events:

"data" returns Object: Fires on each incoming log with the log object as argument.
"changed" returns Object: Fires on each log which was removed from the blockchain. The log will have the additional property "removed: true".
"error" returns Object: Fires when an error in the subscription occurs.
"connected" returns Number: Fires once after the subscription successfully connected. Returns the subscription id.

For the structure of a returned event Object see web3.eth.getPastEvents return values.

Notification returns¶

Object|Null - First parameter is an error object if the subscription failed.
Object - The log object like in web3.eth.getPastEvents return values.


                                        
                                            
             var subscription = web3.eth.subscribe('logs', {
                 address: '0x123456..',
                 topics: ['0x12345...']
             }, function(error, result){
                 if (!error)
                     console.log(result);
             })
             .on("connected", function(subscriptionId){
                 console.log(subscriptionId);
             })
             .on("data", function(log){
                 console.log(log);
             })
             .on("changed", function(log){
             });
                                                                                                                                                  
             // unsubscribes the subscription
             subscription.unsubscribe(function(error, success){
                 if(success)
                     console.log('Successfully unsubscribed!');
             });

Section-4

web3.eth.Contract¶

The web3.eth.Contract object makes it easy to interact with smart contracts on the ethereum blockchain. When you create a new contract object you give it the json interface of the respective smart contract and web3 will auto convert all calls into low level ABI calls over RPC for you.

This allows you to interact with smart contracts as if they were JavaScript objects.

To use it standalone:


                                        
                                            
             var Contract = require('web3-eth-contract');

             // set provider for all later instances to use
             Contract.setProvider('ws://localhost:8546');
                                                                            
             var contract = new Contract(jsonInterface, address);
                                                                            
             contract.methods.somFunc().send({from: ....})
             .on('receipt', function(){
                 ...
             });

new contract¶


                                            
                                                
              new web3.eth.Contract(jsonInterface[, address][, options])

Creates a new contract instance with all its methods and events defined in its json interface object.

Parameters¶

jsonInterface - Object: The json interface for the contract to instantiate
address - String (optional): The address of the smart contract to call.
options - Object (optional): The options of the contract. Some are used as fallbacks for calls and transactions:
- from - String: The address transactions should be made from.
- gasPrice - String: The gas price in wei to use for transactions.
- gas - Number: The maximum gas provided for a transaction (gas limit).
- data - String: The byte code of the contract. Used when the contract gets deployed.

Returns¶

Object: The contract instance with all its methods and events.

Example¶


                                            
                                                
             var myContract = new web3.eth.Contract([...], '0xde0B295669a9FD93d5F28D9Ec85E40f4cb697BAe', {
                 from: '0x1234567890123456789012345678901234567891', // default from address
                 gasPrice: '20000000000' // default gas price in wei, 20 gwei in this case
             });

= Properties =¶

defaultAccount¶


                                            
                                                
             web3.eth.Contract.defaultAccount
             contract.defaultAccount // on contract instance

This default address is used as the default "from" property, if no "from" property is specified in for the following methods:

web3.eth.sendTransaction()
web3.eth.call()
new web3.eth.Contract() -> myContract.methods.myMethod().call()
new web3.eth.Contract() -> myContract.methods.myMethod().send()

Property¶

String - 20 Bytes: Any ethereum address. You should have the private key for that address in your node or keystore. (Default is undefined)

Example¶


                                            
                                                
             web3.eth.defaultAccount;
             > undefined
                                                                                            
             // set the default account
             web3.eth.defaultAccount = '0x11f4d0A3c12e86B4b5F39B213F7E19D048276DAe';

defaultBlock¶


                                            
                                                
             web3.eth.Contract.defaultBlock
             contract.defaultBlock // on contract instance

The default block is used for certain methods. You can override it by passing in the defaultBlock as last parameter. The default value is "latest".

Property¶

The default block parameters can be one of the following:

Number|BN|BigNumber: A block number
"earliest" - String: The genesis block
"latest" - String: The latest block (current head of the blockchain)
"pending" - String: The currently mined block (including pending transactions)

Default is "latest".

Example¶


                                            
                                                
             contract.defaultBlock;
             > "latest"
                                                                                        
             // set the default block
             contract.defaultBlock = 231;

defaultHardfork¶


                                            
                                                
             contract.defaultHardfork

The default hardfork property is used for signing transactions locally.

Property¶

The default hardfork property can be one of the following:

"chainstart" - String
"homestead" - String
"dao" - String
"tangerineWhistle" - String
"spuriousDragon" - String
"byzantium" - String
"constantinople" - String
"petersburg" - String
"istanbul" - String

Default is "petersburg"

Example¶


                                            
                                                
             contract.defaultHardfork;
             > "petersburg"
                                                                                        
             // set the default block
             contract.defaultHardfork = 'istanbul';

defaultChain¶


                                            
                                                
             contract.defaultChain

The default chain property is used for signing transactions locally.

Property¶

The default chain property can be one of the following:

"mainnet" - String
"goerli" - String
"kovan" - String
"rinkeby" - String
"ropsten" - String

Default is "mainnet"

Example¶


                                            
                                                
             contract.defaultChain;
             > "mainnet"
                                                                                   
             // set the default chain
             contract.defaultChain = 'goerli';

defaultCommon¶


                                            
                                                
             contract.defaultCommon

The default common property is used for signing transactions locally.

Property¶

The default common property does contain the following Common object:

customChain - Object: The custom chain properties
- name - string: (optional) The name of the chain
- networkId - number: Network ID of the custom chain
- chainId - number: Chain ID of the custom chain
baseChain - string: (optional) mainnet, goerli, kovan, rinkeby, or ropsten
hardfork - string: (optional) chainstart, homestead, dao, tangerineWhistle, spuriousDragon, byzantium, constantinople, petersburg, or istanbul

Default is undefined.

Example¶


                                            
                                                
             contract.defaultCommon;
             > {customChain: {name: 'custom-network', chainId: 1, networkId: 1}, baseChain: 'mainnet', hardfork: 'petersburg'}
                                                                          
             // set the default common
             contract.defaultCommon = {customChain: {name: 'custom-network', chainId: 1, networkId: 1}, baseChain: 'mainnet', hardfork: 'petersburg'};

transactionBlockTimeout¶


                                            
                                                
             web3.eth.Contract.transcationBlockTimeout
             contract.transactionBlockTimeout // on contract instance

Returns¶

number: The current value of transactionBlockTimeout (default: 50)

transactionConfirmationBlocks¶


                                            
                                                
             web3.eth.Contract.transactionConfirmationBlocks
             contract.transactionConfirmationBlocks // on contract instance

This defines the number of blocks it requires until a transaction is considered confirmed.

Returns¶

number: The current value of transactionConfirmationBlocks (default: 24)

transactionPollingTimeout¶


                                            
                                                
             web3.eth.Contract.transactionPollingTimeout
             contract.transactionPollingTimeout // on contract instance

Returns¶

number: The current value of transactionPollingTimeout (default: 750)

handleRevert¶


                                            
                                                
             web3.eth.Contract.handleRevert
             contract.handleRevert // on contract instance

The handleRevert options property defaults to false and returns the revert reason string if enabled on send or call of a contract method.

Note

The revert reason string and signature are properties on the returned error.

Returns¶

boolean: The current value of handleRevert (default: false)

options¶


                                            
                                                
             myContract.options

The options object for the contract instance. from, gas and gasPrice are used as fallback values when sending transactions.

Properties¶

Object - options:

address - String: The address where the contract is deployed. See options.address.
jsonInterface - Array: The json interface of the contract. See options.jsonInterface.
data - String: The byte code of the contract. Used when the contract gets deployed.
from - String: The address transactions should be made from.
gasPrice - String: The gas price in wei to use for transactions.
gas - Number: The maximum gas provided for a transaction (gas limit).
handleRevert - Boolean: It will otherwise use the default value provided from the Eth module. See handleRevert.
transactionBlockTimeout - Number: It will otherwise use the default value provided from the Eth module. See transactionBlockTimeout.
transactionConfirmationBlocks - Number: It will otherwise use the default value provided from the Eth module. See transactionConfirmationBlocks.
transactionPollingTimeout - Number: It will otherwise use the default value provided from the Eth module. See transactionPollingTimeout.
chain - Number: It will otherwise use the default value provided from the Eth module. See defaultChain.
hardfork - Number: It will otherwise use the default value provided from the Eth module. See defaultHardfork.
common - Number: It will otherwise use the default value provided from the Eth module. See defaultCommon.

Example¶


                                            
                                                
             myContract.options;
             > {
                 address: '0x1234567890123456789012345678901234567891',
                 jsonInterface: [...],
                 from: '0xde0B295669a9FD93d5F28D9Ec85E40f4cb697BAe',
                 gasPrice: '10000000000000',
                 gas: 1000000
             }
                                                                                            
             myContract.options.from = '0x1234567890123456789012345678901234567891'; // default from address
             myContract.options.gasPrice = '20000000000000'; // default gas price in wei
             myContract.options.gas = 5000000; // provide as fallback always 5M gas

options.address¶


                                            
                                                
             myContract.options.address

The address used for this contract instance. All transactions generated by web3.js from this contract will contain this address as the "to".

The address will be stored in lowercase.

Property¶

address - String|null: The address for this contract, or null if not yet set.

Example¶


                                            
                                                
             myContract.options.address;
             > '0xde0b295669a9fd93d5f28d9ec85e40f4cb697bae'
                                                                                                    
             // set a new address
             myContract.options.address = '0x1234FFDD...';

options.jsonInterface¶


                                            
                                                
             myContract.options.jsonInterface

The json interface object derived from the ABI of this contract.

Property¶

jsonInterface - Array: The json interface for this contract. Re-setting this will regenerate the methods and events of the contract instance.

Example¶


                                            
                                                
             myContract.options.jsonInterface;
             > [{
                 "type":"function",
                 "name":"foo",
                 "inputs": [{"name":"a","type":"uint256"}],
                 "outputs": [{"name":"b","type":"address"}]
             },{
                 "type":"event",
                 "name":"Event",
                 "inputs": [{"name":"a","type":"uint256","indexed":true},{"name":"b","type":"bytes32","indexed":false}],
             }]
                                                                                           
             // set a new interface
             myContract.options.jsonInterface = [...];

= Methods =¶

clone¶


                                            
                                                
                                      myContract.clone()

Clones the current contract instance.

Parameters¶

none

Returns¶

Object: The new contract instance.

Example¶


                                            
                                                
             var contract1 = new eth.Contract(abi, address, {gasPrice: '12345678', from: fromAddress});

             var contract2 = contract1.clone();
             contract2.options.address = address2;
                                                                                              
             (contract1.options.address !== contract2.options.address);
             > true

deploy¶


                                            
                                                
             myContract.deploy(options)

Call this function to deploy the contract to the blockchain. After successful deployment the promise will resolve with a new contract instance.

Parameters¶

options - Object: The options used for deployment.
- data - String: The byte code of the contract.
- arguments - Array (optional): The arguments which get passed to the constructor on deployment.

Returns¶

Object: The transaction object:

Array - arguments: The arguments passed to the method before. They can be changed.
Function - send: Will deploy the contract. The promise will resolve with the new contract instance, instead of the receipt!
Function - estimateGas: Will estimate the gas used for deploying. Note: You must specify a from address otherwise you may experience odd behavior.
Function - encodeABI: Encodes the ABI of the deployment, which is contract data + constructor parameters

Example¶


                                            
                                                
             myContract.deploy({
                 data: '0x12345...',
                 arguments: [123, 'My String']
             })
             .send({
                 from: '0x1234567890123456789012345678901234567891',
                 gas: 1500000,
                 gasPrice: '30000000000000'
             }, function(error, transactionHash){ ... })
             .on('error', function(error){ ... })
             .on('transactionHash', function(transactionHash){ ... })
             .on('receipt', function(receipt){
                 console.log(receipt.contractAddress) // contains the new contract address
             })
             .on('confirmation', function(confirmationNumber, receipt){ ... })
             .then(function(newContractInstance){
                 console.log(newContractInstance.options.address) // instance with the new contract address
             });
                                                                                                
                                                                                                
             // When the data is already set as an option to the contract itself
             myContract.options.data = '0x12345...';
                                                                                                
             myContract.deploy({
                 arguments: [123, 'My String']
             })
             .send({
                 from: '0x1234567890123456789012345678901234567891',
                 gas: 1500000,
                 gasPrice: '30000000000000'
             })
             .then(function(newContractInstance){
                 console.log(newContractInstance.options.address) // instance with the new contract address
             });
                                                                                                
                                                                                               
             // Simply encoding
             myContract.deploy({
                 data: '0x12345...',
                 arguments: [123, 'My String']
             })
             .encodeABI();
             > '0x12345...0000012345678765432'
                                                                                                
                                                                                               
             // Gas estimation
             myContract.deploy({
                 data: '0x12345...',
                 arguments: [123, 'My String']
             })
             .estimateGas(function(err, gas){
                 console.log(gas);
             });

methods¶


                                            
                                                
             myContract.methods.myMethod([param1[, param2[, ...]]])

Creates a transaction object for that method, which then can be called, send, estimated, or ABI encoded.

The methods of this smart contract are available through:

The name: myContract.methods.myMethod(123)
The name with parameters: myContract.methods['myMethod(uint256)'](123)
The signature: myContract.methods['0x58cf5f10'](123)

This allows calling functions with same name but different parameters from the JavaScript contract object.

Parameters¶

Parameters of any method depend on the smart contracts methods, defined in the JSON interface.

Returns¶

Object: The transaction object:

Array - arguments: The arguments passed to the method before. They can be changed.
Function - call: Will call the “constant” method and execute its smart contract method in the EVM without sending a transaction (Can’t alter the smart contract state).
Function - send: Will send a transaction to the smart contract and execute its method (Can alter the smart contract state).
Function - estimateGas: Will estimate the gas used when the method would be executed on chain. Note: You must specify a from address otherwise you may experience odd behavior.
Function - encodeABI: Encodes the ABI for this method. This can be send using a transaction, call the method or passing into another smart contracts method as argument.

Example¶


                                            
                                                
             // calling a method

             myContract.methods.myMethod(123).call({from: '0xde0B295669a9FD93d5F28D9Ec85E40f4cb697BAe'}, function(error, result){
                 ...
             });
                                                                                                    
             // or sending and using a promise
             myContract.methods.myMethod(123).send({from: '0xde0B295669a9FD93d5F28D9Ec85E40f4cb697BAe'})
             .then(function(receipt){
                 // receipt can also be a new contract instance, when coming from a "contract.deploy({...}).send()"
             });
                                                                                                   
             // or sending and using the events
                                                                                                    
             myContract.methods.myMethod(123).send({from: '0xde0B295669a9FD93d5F28D9Ec85E40f4cb697BAe'})
             .on('transactionHash', function(hash){
                 ...
             })
             .on('receipt', function(receipt){
                 ...
             })
             .on('confirmation', function(confirmationNumber, receipt){
                 ...
             })
             .on('error', function(error, receipt) {
                 ...
             });

methods.myMethod.call¶


                                            
                                                
             myContract.methods.myMethod([param1[, param2[, ...]]]).call(options [, defaultBlock] [, callback])

Will call a “constant” method and execute its smart contract method in the EVM without sending any transaction. Note calling cannot alter the smart contract state.

Parameters¶

options - Object (optional): The options used for calling.
- from - String (optional): The address the call “transaction” should be made from. For calls the from property is optional however it is highly recommended to explicitly set it or it may default to address(0) depending on your node or provider.
- gasPrice - String (optional): The gas price in wei to use for this call “transaction”.
- gas - Number (optional): The maximum gas provided for this call “transaction” (gas limit).
defaultBlock - Number|String|BN|BigNumber (optional): If you pass this parameter it will not use the default block set with contract.defaultBlock. Pre-defined block numbers as "earliest", "latest", and "pending" can also be used. Useful for requesting data from or replaying transactions in past blocks.
callback - Function (optional): This callback will be fired with the result of the smart contract method execution as the second argument, or with an error object as the first argument.

Returns¶

Promise returns Mixed: The return value(s) of the smart contract method. If it returns a single value, it’s returned as is. If it has multiple return values they are returned as an object with properties and indices:

Example¶


                                            
                                                
             // using the callback
             myContract.methods.myMethod(123).call({from: '0xde0B295669a9FD93d5F28D9Ec85E40f4cb697BAe'}, function(error, result){
                 ...
             });
                                                                                               
             // using the promise
             myContract.methods.myMethod(123).call({from: '0xde0B295669a9FD93d5F28D9Ec85E40f4cb697BAe'})
             .then(function(result){
                 ...
             });
                                                                                                
                                                                                               
             // MULTI-ARGUMENT RETURN:
                                                                                               
             // Solidity
             contract MyContract {
                 function myFunction() returns(uint256 myNumber, string myString) {
                     return (23456, "Hello!%");
                 }
             }
                                                                                               
             // web3.js
             var MyContract = new web3.eth.Contract(abi, address);
             MyContract.methods.myFunction().call()
             .then(console.log);
             > Result {
                 myNumber: '23456',
                 myString: 'Hello!%',
                 0: '23456', // these are here as fallbacks if the name is not know or given
                 1: 'Hello!%'
             }
                                                                                                
                                                                                               
             // SINGLE-ARGUMENT RETURN:
                                                                                          
             // Solidity
             contract MyContract {
                 function myFunction() returns(string myString) {
                     return "Hello!%";
                 }
             }
                                                                                                
             // web3.js
             var MyContract = new web3.eth.Contract(abi, address);
             MyContract.methods.myFunction().call()
             .then(console.log);
             > "Hello!%"

methods.myMethod.send¶


                                            
                                                
             myContract.methods.myMethod([param1[, param2[, ...]]]).send(options[, callback])

Will send a transaction to the smart contract and execute its method. Note this can alter the smart contract state.

Parameters¶

options - Object: The options used for sending.
- from - String: The address the transaction should be sent from.
- gasPrice - String (optional): The gas price in wei to use for this transaction.
- gas - Number (optional): The maximum gas provided for this transaction (gas limit).
- value - ``Number|String|BN|BigNumber``(optional): The value transferred for the transaction in wei.
- nonce - Number (optional): the nonce number of transaction
callback - Function (optional): This callback will be fired first with the “transactionHash”, or with an error object as the first argument.

Returns¶

The callback will return the 32 bytes transaction hash.

PromiEvent: A promise combined event emitter. Resolves when the transaction receipt is available, OR if this send() is called from a someContract.deploy(), then the promise will resolve with the new contract instance. Additionally the following events are available:

sending returns payload: Object: Fired immediately before transmitting the transaction request.
sent returns payload: Object: Fired immediately after the request body has been written to the client, but before the transaction hash is received.
"transactionHash" returns transactionHash: String: Fired when the transaction hash is available.
"receipt" returns receipt: Object: Fired when the transaction receipt is available. Receipts from contracts will have no logs property, but instead an events property with event names as keys and events as properties. See getPastEvents return values for details about the returned event object.
"confirmation" returns confirmation: Number, receipt: Object, latestBlockHash: String: Fired for every confirmation up to the 24th confirmation.
"error" returns error: Error: Fired if an error occurs during sending. If the transaction was rejected by the network with a receipt, the receipt will be available as a property on the error object.

Example¶


                                            
                                                
             // using the callback
             myContract.methods.myMethod(123).send({from: '0xde0B295669a9FD93d5F28D9Ec85E40f4cb697BAe'}, function(error, transactionHash){
                 ...
             });
                                                                                       
             // using the promise
             myContract.methods.myMethod(123).send({from: '0xde0B295669a9FD93d5F28D9Ec85E40f4cb697BAe'})
             .then(function(receipt){
                 // receipt can also be a new contract instance, when coming from a "contract.deploy({...}).send()"
             });
                                                                                       
                                                                                       
             // using the event emitter
             myContract.methods.myMethod(123).send({from: '0xde0B295669a9FD93d5F28D9Ec85E40f4cb697BAe'})
             .on('transactionHash', function(hash){
                 ...
             })
             .on('confirmation', function(confirmationNumber, receipt){
                 ...
             })
             .on('receipt', function(receipt){
                 // receipt example
                 console.log(receipt);
                 > {
                     "transactionHash": "0x9fc76417374aa880d4449a1f7f31ec597f00b1f6f3dd2d66f4c9c6c445836d8b",
                     "transactionIndex": 0,
                     "blockHash": "0xef95f2f1ed3ca60b048b4bf67cde2195961e0bba6f70bcbea9a2c4e133e34b46",
                     "blockNumber": 3,
                     "contractAddress": "0x11f4d0A3c12e86B4b5F39B213F7E19D048276DAe",
                     "cumulativeGasUsed": 314159,
                     "gasUsed": 30234,
                     "events": {
                     "MyEvent": {
                         returnValues: {
                             myIndexedParam: 20,
                             myOtherIndexedParam: '0x123456789...',
                             myNonIndexParam: 'My String'
                         },
                         raw: {
                             data: '0x7f9fade1c0d57a7af66ab4ead79fade1c0d57a7af66ab4ead7c2c2eb7b11a91385',
                             topics: ['0xfd43ade1c09fade1c0d57a7af66ab4ead7c2c2eb7b11a91ffdd57a7af66ab4ead7', '0x7f9fade1c0d57a7af66ab4ead79fade1c0d57a7af66ab4ead7c2c2eb7b11a91385']
                         },
                         event: 'MyEvent',
                         signature: '0xfd43ade1c09fade1c0d57a7af66ab4ead7c2c2eb7b11a91ffdd57a7af66ab4ead7',
                         logIndex: 0,
                         transactionIndex: 0,
                         transactionHash: '0x7f9fade1c0d57a7af66ab4ead79fade1c0d57a7af66ab4ead7c2c2eb7b11a91385',
                         blockHash: '0xfd43ade1c09fade1c0d57a7af66ab4ead7c2c2eb7b11a91ffdd57a7af66ab4ead7',
                         blockNumber: 1234,
                         address: '0xde0B295669a9FD93d5F28D9Ec85E40f4cb697BAe'
                     },
                     "MyOtherEvent": {
                         ...
                     },
                     "MyMultipleEvent":[{...}, {...}] // If there are multiple of the same event, they will be in an array
                 }
             }
         })
         .on('error', function(error, receipt) { // If the transaction was rejected by the network with a receipt, the second parameter will be the receipt.
             ...
         });

methods.myMethod.estimateGas¶


                                            
                                                
         myContract.methods.myMethod([param1[, param2[, ...]]]).estimateGas(options[, callback])

Will call to estimate the gas a method execution will take when executed in the EVM. The estimation can differ from the actual gas used when later sending a transaction, as the state of the smart contract can be different at that time. Note: You must specify a from address otherwise you may experience odd behavior.

Parameters¶

options - Object (optional): The options used for calling.
- from - String (optional): The address the call “transaction” should be made from.
- gas - Number (optional): The maximum gas provided for this call “transaction” (gas limit). Setting a specific value helps to detect out of gas errors. If all gas is used it will return the same number.
- value - Number|String|BN|BigNumber (optional): The value transferred for the call “transaction” in wei.
callback - Function (optional): This callback will be fired with the result of the gas estimation as the second argument, or with an error object as the first argument.

Returns¶

Promise returns Number: The gas amount estimated.

Example¶


                                            
                                                
         // using the callback
         myContract.methods.myMethod(123).estimateGas({gas: 5000000}, function(error, gasAmount){
             if(gasAmount == 5000000)
                 console.log('Method ran out of gas');
         });
                                                                                       
         // using the promise
         myContract.methods.myMethod(123).estimateGas({from: '0xde0B295669a9FD93d5F28D9Ec85E40f4cb697BAe'})
         .then(function(gasAmount){
             ...
         })
         .catch(function(error){
             ...
         });

methods.myMethod.encodeABI¶


                                            
                                                
         myContract.methods.myMethod([param1[, param2[, ...]]]).encodeABI()

Encodes the ABI for this method. The resulting hex string is 32-bit function signature hash plus the passed parameters in Solidity tightly packed format. This can be used to send a transaction, call a method, or pass it into another smart contract’s method as arguments. Set the data field on web3.eth.sendTransaction options as the encodeABI() result and it is the same as calling the contract method with contract.myMethod.send().

Some use cases for encodeABI() include: preparing a smart contract transaction for a multisignature wallet, working with offline wallets and cold storage and creating transaction payload for complex smart contract proxy calls.

Parameters¶

none

Returns¶

String: The encoded ABI byte code to send via a transaction or call.

Example¶


                                            
                                                
         myContract.methods.myMethod(123).encodeABI();
         > '0x58cf5f1000000000000000000000000000000000000000000000000000000000000007B'

= Events =¶

once¶


                                            
                                                
         myContract.once(event[, options], callback)

Subscribes to an event and unsubscribes immediately after the first event or error. Will only fire for a single event.

Parameters¶

event - String: The name of the event in the contract, or "allEvents" to get all events.
options - Object (optional): The options used for deployment.
- filter - Object (optional): Lets you filter events by indexed parameters, e.g. {filter: {myNumber: [12,13]}} means all events where “myNumber” is 12 or 13.
- topics - Array (optional): This allows you to manually set the topics for the event filter. If given the filter property and event signature, (topic[0]) will not be set automatically. Each topic can also be a nested array of topics that behaves as “or” operation between the given nested topics.
callback - Function: This callback will be fired for the first event as the second argument, or an error as the first argument. See getPastEvents return values for details about the event structure.

Returns¶

undefined

Example¶


            
            
            myContract.once('MyEvent', {
                 filter: {myIndexedParam: [20,23], myOtherIndexedParam: '0x123456789...'}, // Using an array means OR: e.g. 20 or 23
                 fromBlock: 0
            }, function(error, event){ console.log(event); });
                                                                                   
            // event output example
            > {
                 returnValues: {
                     myIndexedParam: 20,
                     myOtherIndexedParam: '0x123456789...',
                     myNonIndexParam: 'My String'
                 },
                 raw: {
                     data: '0x7f9fade1c0d57a7af66ab4ead79fade1c0d57a7af66ab4ead7c2c2eb7b11a91385',
                     topics: ['0xfd43ade1c09fade1c0d57a7af66ab4ead7c2c2eb7b11a91ffdd57a7af66ab4ead7', '0x7f9fade1c0d57a7af66ab4ead79fade1c0d57a7af66ab4ead7c2c2eb7b11a91385']
                 },
                 event: 'MyEvent',
                 signature: '0xfd43ade1c09fade1c0d57a7af66ab4ead7c2c2eb7b11a91ffdd57a7af66ab4ead7',
                 logIndex: 0,
                 transactionIndex: 0,
                 transactionHash: '0x7f9fade1c0d57a7af66ab4ead79fade1c0d57a7af66ab4ead7c2c2eb7b11a91385',
                 blockHash: '0xfd43ade1c09fade1c0d57a7af66ab4ead7c2c2eb7b11a91ffdd57a7af66ab4ead7',
                 blockNumber: 1234,
                 address: '0xde0B295669a9FD93d5F28D9Ec85E40f4cb697BAe'
            }

events¶


            
            
            myContract.events.MyEvent([options][, callback])

Subscribe to an event.

Parameters¶

options - Object (optional): The options used for deployment.
- filter - Object (optional): Let you filter events by indexed parameters, e.g. {filter: {myNumber: [12,13]}} means all events where “myNumber” is 12 or 13.
- fromBlock - Number|String|BN|BigNumber (optional): The block number (greater than or equal to) from which to get events on. Pre-defined block numbers as "earliest", "latest" and "pending" can also be used. For specific range use getPastEvents.
- topics - Array (optional): This allows to manually set the topics for the event filter. If given the filter property and event signature, (topic[0]) will not be set automatically. Each topic can also be a nested array of topics that behaves as “or” operation between the given nested topics.
callback - Function (optional): This callback will be fired for each event as the second argument, or an error as the first argument.

Returns¶

EventEmitter: The event emitter has the following events:

"data" returns Object: Fires on each incoming event with the event object as argument.
"changed" returns Object: Fires on each event which was removed from the blockchain. The event will have the additional property "removed: true".
"error" returns Object: Fires when an error in the subscription occours.
"connected" returns String: Fires once after the subscription successfully connected. Returns the subscription id.

The structure of the returned event Object looks as follows:

event - String: The event name.
signature - String|Null: The event signature, null if it’s an anonymous event.
address - String: Address this event originated from.
returnValues - Object: The return values coming from the event, e.g. {myVar: 1, myVar2: '0x234...'}.
logIndex - Number: Integer of the event index position in the block.
transactionIndex - Number: Integer of the transaction’s index position the event was created in.
transactionHash 32 Bytes - String: Hash of the transaction this event was created in.
blockHash 32 Bytes - String: Hash of the block this event was created in. null when it’s still pending.
blockNumber - Number: The block number this log was created in. null when still pending.
raw.data - String: The data containing non-indexed log parameter.
raw.topics - Array: An array with max 4 32 Byte topics, topic 1-3 contains indexed parameters of the event.

Example¶


            
            
            myContract.events.MyEvent({
                 filter: {myIndexedParam: [20,23], myOtherIndexedParam: '0x123456789...'}, // Using an array means OR: e.g. 20 or 23
                 fromBlock: 0
            }, function(error, event){ console.log(event); })
            .on("connected", function(subscriptionId){
                 console.log(subscriptionId);
            })
            .on('data', function(event){
                 console.log(event); // same results as the optional callback above
            })
            .on('changed', function(event){
                 // remove event from local database
            })
            .on('error', function(error, receipt) { // If the transaction was rejected by the network with a receipt, the second parameter will be the receipt.
                 ...
            });
                                                                                   
            // event output example
            > {
                 returnValues: {
                     myIndexedParam: 20,
                     myOtherIndexedParam: '0x123456789...',
                     myNonIndexParam: 'My String'
                 },
                 raw: {
                     data: '0x7f9fade1c0d57a7af66ab4ead79fade1c0d57a7af66ab4ead7c2c2eb7b11a91385',
                     topics: ['0xfd43ade1c09fade1c0d57a7af66ab4ead7c2c2eb7b11a91ffdd57a7af66ab4ead7', '0x7f9fade1c0d57a7af66ab4ead79fade1c0d57a7af66ab4ead7c2c2eb7b11a91385']
                 },
                 event: 'MyEvent',
                 signature: '0xfd43ade1c09fade1c0d57a7af66ab4ead7c2c2eb7b11a91ffdd57a7af66ab4ead7',
                 logIndex: 0,
                 transactionIndex: 0,
                 transactionHash: '0x7f9fade1c0d57a7af66ab4ead79fade1c0d57a7af66ab4ead7c2c2eb7b11a91385',
                 blockHash: '0xfd43ade1c09fade1c0d57a7af66ab4ead7c2c2eb7b11a91ffdd57a7af66ab4ead7',
                 blockNumber: 1234,
                 address: '0xde0B295669a9FD93d5F28D9Ec85E40f4cb697BAe'
            }

events.allEvents¶


            
            
            myContract.events.allEvents([options][, callback])

Same as events but receives all events from this smart contract. Optionally the filter property can filter those events.

getPastEvents¶


            
            
            myContract.getPastEvents(event[, options][, callback])

Gets past events for this contract.

Parameters¶

event - String: The name of the event in the contract, or "allEvents" to get all events.
options - Object (optional): The options used for deployment.
- filter - Object (optional): Lets you filter events by indexed parameters, e.g. {filter: {myNumber: [12,13]}} means all events where “myNumber” is 12 or 13.
- fromBlock - Number|String|BN|BigNumber (optional): The block number (greater than or equal to) from which to get events on. Pre-defined block numbers as "earliest", "latest" and "pending" can also be used.
- toBlock - Number|String|BN|BigNumber (optional): The block number (less than or equal to) to get events up to (Defaults to "latest"). Pre-defined block numbers as "earliest", "latest" and "pending" can also be used.
- topics - Array (optional): This allows manually setting the topics for the event filter. If given the filter property and event signature, (topic[0]) will not be set automatically. Each topic can also be a nested array of topics that behaves as “or” operation between the given nested topics.
callback - Function (optional): This callback will be fired with an array of event logs as the second argument, or an error as the first argument.

Returns¶

Promise returns Array: An array with the past event Objects, matching the given event name and filter.

For the structure of a returned event Object see getPastEvents return values.

Example¶


                
                
                myContract.getPastEvents('MyEvent', {
                     filter: {myIndexedParam: [20,23], myOtherIndexedParam: '0x123456789...'}, // Using an array means OR: e.g. 20 or 23
                     fromBlock: 0,
                     toBlock: 'latest'
                }, function(error, events){ console.log(events); })
                .then(function(events){
                     console.log(events) // same results as the optional callback above
                });
                                                                           
                > [{
                     returnValues: {
                         myIndexedParam: 20,
                         myOtherIndexedParam: '0x123456789...',
                         myNonIndexParam: 'My String'
                     },
                     raw: {
                         data: '0x7f9fade1c0d57a7af66ab4ead79fade1c0d57a7af66ab4ead7c2c2eb7b11a91385',
                         topics: ['0xfd43ade1c09fade1c0d57a7af66ab4ead7c2c2eb7b11a91ffdd57a7af66ab4ead7', '0x7f9fade1c0d57a7af66ab4ead79fade1c0d57a7af66ab4ead7c2c2eb7b11a91385']
                     },
                     event: 'MyEvent',
                     signature: '0xfd43ade1c09fade1c0d57a7af66ab4ead7c2c2eb7b11a91ffdd57a7af66ab4ead7',
                     logIndex: 0,
                     transactionIndex: 0,
                     transactionHash: '0x7f9fade1c0d57a7af66ab4ead79fade1c0d57a7af66ab4ead7c2c2eb7b11a91385',
                     blockHash: '0xfd43ade1c09fade1c0d57a7af66ab4ead7c2c2eb7b11a91ffdd57a7af66ab4ead7',
                     blockNumber: 1234,
                     address: '0xde0B295669a9FD93d5F28D9Ec85E40f4cb697BAe'
                },{
                     ...
                }]

Getting Started

Adding web3.js

Web3

Web3.modules

Returns¶

Example¶

Web3 Instance ¶

version¶

Returns¶

Example¶

utils¶

setProvider¶

Parameters¶

Returns¶

Example: Local Geth Node¶

Example: Remote Node Provider¶

providers¶

Value¶

Example¶

Configuration¶

givenProvider¶

Returns¶

Example¶

currentProvider¶

Returns¶

Example¶

BatchRequest¶

Parameters¶

Returns¶

Example¶

extend¶

Parameters¶

Returns¶

Example¶

Section-2

web3.eth¶

Note on checksum addresses¶

Example¶

subscribe¶

Contract¶

Iban¶

personal¶

accounts¶

ens¶

abi¶

net¶

setProvider¶

Parameters¶

Returns¶

Example: Local Geth Node¶

Example: Remote Node Provider¶

providers¶

Value¶

Example¶

Configuration¶

givenProvider¶

Returns¶

Example¶

currentProvider¶

Returns¶

Example¶

BatchRequest¶

Parameters¶

Returns¶

Example¶

extend¶

Parameters¶

Returns¶

Example¶

defaultAccount¶

Property¶

Example¶

defaultBlock¶

Property¶

Example¶

defaultHardfork¶

Example¶

defaultChain¶

Property¶

Example¶