Ethers.js: Complete Ethereum JavaScript Library

import { ethers } from 'ethers';

async function checkBalance() {
  // Connect to Ethereum mainnet using a public RPC
  const provider = new ethers.JsonRpcProvider('https://eth.llamarpc.com');
  
  // Address to check balance for
  const address = '0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045';
  
  try {
    // Get the current balance in wei
    const balanceWei = await provider.getBalance(address);
    
    // Convert wei to ether for readable format
    const balanceEth = ethers.formatEther(balanceWei);
    
    console.log(`Address: ${address}`);
    console.log(`Balance: ${balanceEth} ETH`);
    
    // Get current block number
    const blockNumber = await provider.getBlockNumber();
    console.log(`Current block: ${blockNumber}`);
    
    // Get network information
    const network = await provider.getNetwork();
    console.log(`Network: ${network.name} (Chain ID: ${network.chainId})`);
    
  } catch (error) {
    console.error('Error fetching balance:', error);
  }
}

checkBalance();