web3-eth-abi

What is web3-eth-abi?

The web3-eth-abi package is a part of the Web3.js library and is used for encoding and decoding Ethereum ABI (Application Binary Interface) data. It allows developers to interact with smart contracts by encoding function calls and decoding the data returned by smart contracts.

What are web3-eth-abi's main functionalities?

Encoding Function Calls

This feature allows you to encode function calls to be sent to the Ethereum blockchain. The code sample demonstrates how to encode a function call with a uint256 and a string parameter.

const Web3 = require('web3');
const web3 = new Web3();
const abi = require('web3-eth-abi');

const functionSignature = 'myMethod(uint256,string)';
const parameters = [123, 'Hello World'];
const encodedData = abi.encodeFunctionCall({
  name: 'myMethod',
  type: 'function',
  inputs: [{ type: 'uint256', name: 'myNumber' }, { type: 'string', name: 'myString' }]
}, parameters);

console.log(encodedData);

Decoding Function Return Values

This feature allows you to decode the return values from a smart contract function call. The code sample demonstrates how to decode a return value that includes a uint256 and a string.

const Web3 = require('web3');
const web3 = new Web3();
const abi = require('web3-eth-abi');

const encodedReturnValue = '0x000000000000000000000000000000000000000000000000000000000000007b000000000000000000000000000000000000000000000000000000000000000b48656c6c6f20576f726c64000000000000000000000000000000000000000000';
const decodedData = abi.decodeParameters(['uint256', 'string'], encodedReturnValue);

console.log(decodedData);

Encoding Event Logs

This feature allows you to encode event logs for smart contracts. The code sample demonstrates how to encode an event log with a uint256 and a string parameter.

const Web3 = require('web3');
const web3 = new Web3();
const abi = require('web3-eth-abi');

const eventSignature = 'MyEvent(uint256,string)';
const parameters = [123, 'Hello World'];
const encodedEvent = abi.encodeEventSignature({
  name: 'MyEvent',
  type: 'event',
  inputs: [{ type: 'uint256', name: 'myNumber' }, { type: 'string', name: 'myString' }]
});

console.log(encodedEvent);

Decoding Event Logs

This feature allows you to decode event logs from smart contracts. The code sample demonstrates how to decode an event log that includes a uint256 and a string.

const Web3 = require('web3');
const web3 = new Web3();
const abi = require('web3-eth-abi');

const encodedLog = '0x000000000000000000000000000000000000000000000000000000000000007b000000000000000000000000000000000000000000000000000000000000000b48656c6c6f20576f726c64000000000000000000000000000000000000000000';
const decodedLog = abi.decodeLog([
  { type: 'uint256', name: 'myNumber' },
  { type: 'string', name: 'myString' }
], encodedLog, []);

console.log(decodedLog);

Other packages similar to web3-eth-abi

ethers

The ethers.js library is a complete and compact library for interacting with the Ethereum blockchain. It provides similar functionalities for encoding and decoding ABI data, but also includes additional features such as wallet management, contract interaction, and provider management. Ethers.js is known for its simplicity and ease of use.

ethjs-abi

The ethjs-abi package is a lightweight library for encoding and decoding Ethereum ABI data. It provides similar functionalities to web3-eth-abi but is designed to be minimal and efficient. It is part of the ethjs suite of tools, which are known for their modularity and small footprint.

README

web3.js - Web3-Eth-Abi

This is a sub-package of web3.js.

web3-eth-abi contains functions for the encode and decode EVM in/output.

Installation

You can install the package either using NPM or using Yarn

Using NPM

npm install web3-eth-abi

Using Yarn

yarn add web3-eth-abi

Getting Started

• :writing_hand: If you have questions submit an issue or join us on Discord

Prerequisites

• :gear: NodeJS (LTS/Fermium)
• :toolbox: Yarn/Lerna

Package.json Scripts

Script	Description
clean	Uses rimraf to remove dist/
build	Uses tsc to build package and dependent packages
lint	Uses eslint to lint package
lint:fix	Uses eslint to check and fix any warnings
format	Uses prettier to format the code
test	Uses jest to run unit tests
test:integration	Uses jest to run tests under /test/integration
test:unit	Uses jest to run tests under /test/unit