Introduction to Ethers.js

Ethers.js is a lightweight JavaScript library designed to interact with the Ethereum blockchain. It is widely used in building decentralized applications (DApps) and is known for its security, modularity, and simplicity. Compared to Web3.js, Ethers.js offers a more modern, secure, and developer-friendly API, making it a popular choice for Web3 development.

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Why Use Ethers.js?

• Lightweight: Smaller package size compared to Web3.js.
• Secure: Designed with strong security practices.
• Fully TypeScript compatible: Ideal for modern front-end and backend development.
• Complete Wallet Management: Supports creating, importing, encrypting, and signing wallets.
• Built-in ENS support: Easily resolve Ethereum Name Service names.
• Provider abstraction: Allows seamless switching between different Ethereum nodes (Infura, Alchemy, JSON-RPC, etc.).

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Installation

Install via npm:

bashCopyEditnpm install ethers

For use in HTML directly:

<script src="https://cdn.ethers.io/lib/ethers-5.2.umd.min.js"></script>

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Basic Structure

Ethers.js is divided into several key components:

1. Provider – Connects to the Ethereum network.
2. Signer – Represents an Ethereum account that can sign messages and transactions.
3. Contract – Interacts with smart contracts.
4. Utils – Provides utility functions like encoding, hashing, etc.
5. Wallet – Manages keys and signs transactions.

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Connecting to Ethereum

You can connect to Ethereum using a Provider:

const { ethers } = require('ethers');

// Connect to the Ethereum mainnet using a default provider
const provider = ethers.getDefaultProvider('mainnet');

Or via Infura:

const provider = new ethers.providers.InfuraProvider('mainnet', 'YOUR_INFURA_PROJECT_ID');

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Getting Wallet Information

Create a new wallet:

const wallet = ethers.Wallet.createRandom();
console.log(wallet.address);

Or connect an existing wallet:

const privateKey = '0xYOUR_PRIVATE_KEY';
const wallet = new ethers.Wallet(privateKey, provider);

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Interacting with the Blockchain

1. Get Balance

const balance = await provider.getBalance('0xAddress');
console.log(ethers.utils.formatEther(balance)); // Converts Wei to Ether

2. Send Ether

const tx = await wallet.sendTransaction({
  to: '0xRecipientAddress',
  value: ethers.utils.parseEther('0.01')
});
await tx.wait();
console.log('Transaction successful:', tx.hash);

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Working with Smart Contracts

To interact with a smart contract, you need the contract’s ABI and address:

const contract = new ethers.Contract(contractAddress, contractABI, wallet);

Call a Read Function

const value = await contract.getValue();
console.log(value);

Call a Write Function

const tx = await contract.setValue(42);
await tx.wait();

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Listening to Events

contract.on('ValueChanged', (oldValue, newValue) => {
  console.log(`Value changed from ${oldValue} to ${newValue}`);
});

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Utilities in Ethers.js

• Convert Ether and Wei:

ethers.utils.parseEther('1.0');  // => BigNumber in Wei
ethers.utils.formatEther('1000000000000000000'); // => '1.0'

• Hashing:

ethers.utils.keccak256(ethers.utils.toUtf8Bytes('hello'));

• Signing messages:

javascriptCopyEditconst message = "Hello Ethereum!";
const signature = await wallet.signMessage(message);
console.log(signature);

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Ethers.js vs Web3.js

Feature	Ethers.js	Web3.js
Package Size	Small (~100KB)	Larger
TypeScript Support	Full	Partial
Modular Design	Yes	Limited
Wallet Integration	Built-in	Requires external
Modern Syntax	ES6+ Promises	Callback-based (v1)