web3-eth-contract

What is web3-eth-contract?

The web3-eth-contract package is part of the Web3.js library and is used to interact with Ethereum smart contracts. It allows you to deploy, call, and listen to smart contract events on the Ethereum blockchain.

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

Deploying a Contract

This feature allows you to deploy a new smart contract to the Ethereum blockchain. The code sample demonstrates how to use the web3-eth-contract package to deploy a contract using its ABI and bytecode.

const Web3 = require('web3');
const web3 = new Web3('http://localhost:8545');
const contractABI = [ /* ABI array */ ];
const contractBytecode = '0x...';
const deployContract = async () => {
  const accounts = await web3.eth.getAccounts();
  const contract = new web3.eth.Contract(contractABI);
  const deployedContract = await contract.deploy({ data: contractBytecode }).send({ from: accounts[0], gas: 1500000, gasPrice: '30000000000000' });
  console.log('Contract deployed at address:', deployedContract.options.address);
};
deployContract();

Calling a Contract Method

This feature allows you to call a method on an already deployed smart contract. The code sample demonstrates how to call a method named 'myMethod' on a contract using its ABI and address.

const Web3 = require('web3');
const web3 = new Web3('http://localhost:8545');
const contractABI = [ /* ABI array */ ];
const contractAddress = '0x...';
const contract = new web3.eth.Contract(contractABI, contractAddress);
const callMethod = async () => {
  const result = await contract.methods.myMethod().call();
  console.log('Method call result:', result);
};
callMethod();

Listening to Contract Events

This feature allows you to listen for events emitted by a smart contract. The code sample demonstrates how to listen for an event named 'MyEvent' from a contract using its ABI and address.

const Web3 = require('web3');
const web3 = new Web3('http://localhost:8545');
const contractABI = [ /* ABI array */ ];
const contractAddress = '0x...';
const contract = new web3.eth.Contract(contractABI, contractAddress);
contract.events.MyEvent({
  fromBlock: 0
}, (error, event) => {
  if (error) {
    console.error('Error:', error);
  } else {
    console.log('Event:', event);
  }
});

Other packages similar to web3-eth-contract

ethers

The ethers.js library is a complete and compact library for interacting with the Ethereum blockchain and its ecosystem. It provides similar functionalities to web3-eth-contract, such as deploying contracts, calling contract methods, and listening to events. Ethers.js is known for its simplicity and ease of use.

truffle-contract

Truffle Contract is a part of the Truffle Suite and provides a better abstraction for interacting with Ethereum smart contracts. It offers similar functionalities to web3-eth-contract, including contract deployment, method calls, and event listening. Truffle Contract is tightly integrated with the Truffle framework, making it a good choice for developers using Truffle for their Ethereum development.

embark

Embark is a framework for developing and deploying decentralized applications (dApps) that integrates with Ethereum smart contracts. It provides functionalities similar to web3-eth-contract, such as contract deployment, method calls, and event listening. Embark is known for its powerful features and ease of use, especially for building complex dApps.

README

web3-eth-contract

This is a sub package of web3.js

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

Installation

Node.js

npm install web3-eth-contract

In the Browser

Build running the following in the web3.js repository:

npm run-script build-all

Then include dist/web3-eth-contract.js in your html file. This will expose the Web3EthContract object on the window object.

Usage

// in node.js
var Web3EthContract = require('web3-eth-contract');

// set provider for all later instances to use
Web3EthContract.setProvider('ws://localhost:8546');

var contract = new Web3EthContract(jsonInterface, address);
contract.methods.somFunc().send({from: ....})
.on('receipt', function(){
    ...
});