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Web3.js Config Guide

Configuration parameters​

There is list of configuration params that can be set for modifying behavior of different functions in web3.js packages. Following is list of configuration options with details:

Global level Config​

There is option of modifying any of above-mentioned configuration parameter at global level when instantiating Web3, and it will be available to all packages.

import { Web3 } from 'web3';

const web3 = new Web3({
  provider: 'https://mainnet.infura.io/v3/YOURID',
  config: {
    defaultTransactionType: '0x0',
  },
});

//now default transaction type will be 0x0 so using following function in eth will send type 0x0 transaction

web3.eth
  .sendTransaction({
    from: '0x18532dF2Ab835d4E9D07a8b9B759bf5F8f890f49',
    to: '0xB2f70d8965e754cc07D343a9b5332876D3070155',
    value: 100,
    gasLimit: 21000,
  })
  .then((res) => console.log(res));

For Advance Users: Global level config can also be set using Web3Context object.

import { Web3, Web3Context } from 'web3';

const context = new Web3Context('http://127.0.0.1:7545');
context.setConfig({ defaultTransactionType: '0x0' });

const web3 = new Web3(context);

//it will not default to 0x0 type transactions
web3.eth.sendTransaction({
    from: '0x18532dF2Ab835d4E9D07a8b9B759bf5F8f890f49',
    to: '0x018e221145dE7cefAD09BD53F41c11A918Bf1Cb7',
    value: 100,
    gasLimit: 21000
}).then(res => console.log(res));

Package level config​

Setting config in Individual Package under Web3 instance​

Some configuration options that effects selected packages can be modified using setConfig(...) function.

import { Web3 } from 'web3';

const web3 = new Web3('https://mainnet.infura.io/v3/YOURID');

web3.eth.setConfig({ defaultTransactionType: '0x0'});

web3.eth
  .sendTransaction({
    from: '0x18532dF2Ab835d4E9D07a8b9B759bf5F8f890f49',
    to: '0xB2f70d8965e754cc07D343a9b5332876D3070155',
    value: 100,
    gasLimit: 21000,
  })
  .then((res) => console.log(res));

Setting config in Individually imported Packages​

If an individual package is being imported instead of whole web3.js, there is option of setting config params by passing config in constructors or by using setConfig(...) function:

For example if only web3Eth package is installed using:

npm i web3-eth

Configuration options can be set by passing in constructor:

setConfig in the constructor
import { Web3Eth } from 'web3-eth';

const web3EthObj = new Web3Eth({
  provider: 'http://127.0.0.1:7545',
  config: {
    defaultTransactionType: 0x0,
  },
});

web3EthObj
  .sendTransaction({
    from: '0x18532dF2Ab835d4E9D07a8b9B759bf5F8f890f49',
    to: '0x018e221145dE7cefAD09BD53F41c11A918Bf1Cb7',
    value: 100,
    gasLimit: 21000,
  })
  .then((res) => console.log(res));

Another way of setting config for individually imported package is by using setConfig(...) function.

setConfig function
import { Web3Eth } from 'web3-eth';

const web3EthObj = new Web3Eth('http://127.0.0.1:7545');

web3EthObj.setConfig({ defaultTransactionType: 0x0 });

web3EthObj
  .sendTransaction({
    from: '0x18532dF2Ab835d4E9D07a8b9B759bf5F8f890f49',
    to: '0x018e221145dE7cefAD09BD53F41c11A918Bf1Cb7',
    value: 100,
    gasLimit: 21000,
  })
  .then((res) => console.log(res));

Getting Current Config​

For getting list of current config params getContextObject().config can be used as :

getContextObject() in Web3 object
import { Web3 } from 'web3';

const web3 = new Web3('http://127.0.0.1:7545');

console.log(web3.getContextObject().config)
/* ↳
  handleRevert: false,
  defaultAccount: undefined,
  defaultBlock: 'latest',
  transactionBlockTimeout: 50,
  transactionConfirmationBlocks: 24,
  transactionPollingInterval: 1000,
  transactionPollingTimeout: 750000,
  transactionReceiptPollingInterval: undefined,
  transactionSendTimeout: 750000,
  transactionConfirmationPollingInterval: undefined,
  blockHeaderTimeout: 10,
  maxListenersWarningThreshold: 100,
  contractDataInputFill: 'input',
  defaultNetworkId: undefined,
  defaultChain: 'mainnet',
  defaultHardfork: 'london',
  defaultCommon: undefined,
  defaultTransactionType: '0x2',
  defaultMaxPriorityFeePerGas: '0x9502f900',
 ...
*/

For individually imported packages same approach can be used to get current config params.

getContextObject() in an imported package
import { Web3Eth } from 'web3';

const web3 = new Web3Eth('http://127.0.0.1:7545');

console.log(web3.getContextObject().config)
/* ↳
  handleRevert: false,
  defaultAccount: undefined,
  defaultBlock: 'latest',
  transactionBlockTimeout: 50,
  transactionConfirmationBlocks: 24,
  transactionPollingInterval: 1000,
  transactionPollingTimeout: 750000,
  ...
*/

defaultReturnFormat​

The defaultReturnFormat allows users to specify the format in which certain types of data should be returned by default. It is a configuration parameter that can be set at the global level and affects how data is returned across the entire library.

import { Web3, FMT_NUMBER, FMT_BYTES } from 'web3';

web3.defaultReturnFormat = {
    number: FMT_NUMBER.BIGINT,
    bytes: FMT_BYTES.HEX,
};

info

The defaultReturnFormat can be configured both globally and at the package level:

import { Web3Eth, FMT_NUMBER, FMT_BYTES } from 'web3-eth';

const eth = new Web3Eth()
eth.defaultReturnFormat = {
    number: FMT_NUMBER.BIGINT,
    bytes: FMT_BYTES.HEX,
};

All available choices for numeric data:​

export enum FMT_NUMBER {
    NUMBER = 'NUMBER_NUMBER',
    HEX = 'NUMBER_HEX',
    STR = 'NUMBER_STR',
    BIGINT = 'NUMBER_BIGINT',
}

All available choices for bytes data:​

export enum FMT_BYTES {
    HEX = 'BYTES_HEX',
    UINT8ARRAY = 'BYTES_UINT8ARRAY',
}