Ethereum Development Tutorials, Guides & Insights

• Use crypto.randomBytes when:
• You are building Node.js applications without blockchain-specific functionality.
• You want to avoid adding external dependencies.
• Use ethers.randomBytes when:
• You are developing Ethereum-related applications and already have ethers.js in your project.
• You want the flexibility of generating random bytes with minimal configuration, defaulting to 32 bytes for Ethereum addresses or private keys.

• Contract Address: Replace '0xTokenContractAddress' with the address of the ERC-20 token (e.g., USDT, DAI, or any other ERC-20 token).
• Wallet Address: Replace '0xYourEthereumAddress' with the wallet address whose token balance you want to query.
• ABI: We are using a minimal ABI with just the balanceOf function, which is all that’s required to query the token balance.

Once you’ve added the code, run the script:

const ethers = require('ethers');

// Replace with your Infura Project ID
const infuraProvider = new ethers.JsonRpcProvider('https://mainnet.infura.io/v3/YOUR_INFURA_PROJECT_ID');

// Replace with your wallet's private key
const privateKey = 'YOUR_PRIVATE_KEY';

// Create a wallet instance and connect it to Infura
const wallet = new ethers.Wallet(privateKey, infuraProvider);

// Replace with the recipient's Ethereum address
const recipientAddress = '0xRecipientEthereumAddress';

// Amount to send (in Ether)
const amountInEther = '0.01';

async function sendTransaction() {
  try {
    const tx = {
      to: recipientAddress,
      value: ethers.utils.parseEther(amountInEther),
      gasLimit: 21000, // Gas limit for a basic transaction
      gasPrice: await infuraProvider.getGasPrice() // Get current gas price from Infura
    };

    // Send the transaction
    const transaction = await wallet.sendTransaction(tx);
    console.log('Transaction Hash:', transaction.hash);

    // Wait for the transaction to be mined
    const receipt = await transaction.wait();
    console.log('Transaction Confirmed:', receipt);
  } catch (error) {
    console.error('Error sending transaction:', error);
  }
}

sendTransaction();

• API: This script uses Infura’s node access and Ethers.js to send Ether in real-time.
• Use Case: Essential for dApps, wallets, or any application needing to send transactions or interact with the blockchain live.

const ethers = require('ethers');

// Replace with your Infura Project ID
const infuraProvider = new ethers.JsonRpcProvider('https://mainnet.infura.io/v3/YOUR_INFURA_PROJECT_ID');

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

// Replace with the wallet address to query the balance
const walletAddress = '0xYourWalletAddress';

// ABI of the ERC-20 token (we only need the balanceOf function here)
const abi = [
    'function balanceOf(address owner) view returns (uint256)'
];

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

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

        // Convert the balance from wei (for ERC-20 tokens, it could be small denominations)
        console.log(`Token Balance: ${balance.toString()}`);
    } catch (error) {
        console.error('Error fetching token balance:', error);
    }
}

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

• Contract Address: Replace '0xTokenContractAddress' with the ERC-20 token contract’s address (for example, USDT, DAI, etc.).
• Wallet Address: Replace '0xYourWalletAddress' with the wallet address whose balance you want to query.
• ABI (Application Binary Interface): The ABI specifies the functions and data structures used in the smart contract. In this case, we’re using a simple balanceOf function to query the balance.

   https://api.etherscan.io/api?module=account&action=txlist&address=0xYourEthereumAddress&startblock=0&endblock=99999999&sort=asc&apikey=YOUR_API_KEY

   https://api.etherscan.io/api?module=account&action=tokentx&address=0xYourEthereumAddress&startblock=0&endblock=99999999&sort=asc&apikey=YOUR_API_KEY