Blockchain Development Programming Tutorials, Guides & Best Practices

In this step, we will use Ethers.js to query the balance of an ERC-20 token for a specific Ethereum address.

const ethers = require('ethers');

// Replace with your Infura or other Ethereum node provider URL
const provider = new ethers.JsonRpcProvider('https://mainnet.infura.io/v3/YOUR_INFURA_PROJECT_ID');

// Replace with the ERC-20 token contract address (e.g., USDT, DAI)
const contractAddress = '0xTokenContractAddress';

// Replace with the wallet address you want to query
const walletAddress = '0xYourEthereumAddress';

// ERC-20 token ABI (just the balanceOf function)
const abi = [
    'function balanceOf(address owner) view returns (uint256)'
];

// Create a contract instance
const contract = new ethers.Contract(contractAddress, abi, provider);

async function getTokenBalance() {
    try {
        // Query the balance
        const balance = await contract.balanceOf(walletAddress);

        // Convert balance to a human-readable format (tokens usually have 18 decimals)
        const formattedBalance = ethers.utils.formatUnits(balance, 18);

        console.log(`Token Balance: ${formattedBalance}`);
    } catch (error) {
        console.error('Error fetching token balance:', error);
    }
}

// Call the function to get the token balance
getTokenBalance();

• Bytecode and ABI: The contract bytecode is the compiled contract, and the ABI defines the contract’s interface. You need both to deploy the contract.
• The contract will be deployed using your Infura provider and wallet, and once mined, it will return the deployed contract address.

In this tutorial, you learned how to use Ethers.js with Infura to send Ether, interact with smart contracts, and deploy contracts on the Ethereum blockchain. This setup allows you to interact with the blockchain in real-time without the need to run your own Ethereum node, making it easier to develop decentralized applications (dApps) and other blockchain-based services.

These endpoints give you the flexibility to retrieve detailed blockchain data and customize your applications accordingly.

In this tutorial, you learned how to interact with the Ethereum blockchain using the Etherscan API. You successfully queried Ethereum wallet balances, transaction details, and ERC-20 token balances. By using the Etherscan API, you can easily access blockchain data without needing to run your own Ethereum node.