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-eth-abi

This is a sub package of web3.js

This is the abi package to be used in the web3-eth package. Please read the documentation for more.

Installation

Node.js

npm install web3-eth-abi

In the Browser

Build running the following in the web3.js repository:

npm run-script build-all

Then include dist/web3-eth-abi.js in your html file. This will expose the Web3EthAbi object on the window object.

Usage

// in node.js
var Web3EthAbi = require('web3-eth-abi');

Web3EthAbi.encodeFunctionSignature('myMethod(uint256,string)');
> '0x24ee0097'