Blockchain Development Programming Tutorials, Guides & Best Practices

Both crypto.randomBytes and ethers.randomBytes generate cryptographically secure random bytes, meaning the bytes are suitable for use in cryptographic applications such as key generation, encryption, and other security-sensitive operations.

• 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.

const num1 = BigNumber.from(10);
const num2 = BigNumber.from(5);

console.log(num1.add(num2).toString()); // "15"
console.log(num1.sub(num2).toString()); // "5"

BigNumber instances can be compared using various methods such as eq (equals), lt (less than), and gt (greater than).

You should see the token balance printed in the console, in a human-readable format (typically with 18 decimals for ERC-20 tokens).

Now let’s query the ERC-20 token transfer history for a specific wallet address using the Etherscan API.

• Data Analytics: Use Etherscan if you need to fetch historical data, such as transaction histories, token balances, or account balances.
• Blockchain Explorers: Ideal for building tools similar to Etherscan itself, where you query and display blockchain data to users.
• Read-Only Data: You can’t send transactions, but you can retrieve information about any Ethereum address, smart contract, or token transfer.

• Decentralized Applications (dApps): If you’re building an application that needs to interact with Ethereum in real-time, such as sending transactions or calling smart contract functions.
• Wallets: If you are developing a wallet application that needs to sign and broadcast transactions.
• Smart Contract Deployment: Use Infura to deploy or interact with smart contracts on the Ethereum blockchain.

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 {
        // Convert Ether to Wei (the smallest unit of Ether)
        const amountInWei = ethers.utils.parseEther(amountInEther);

        // Create the transaction
        const tx = {
            to: recipientAddress,
            value: amountInWei,
            gasLimit: ethers.utils.hexlify(21000), // Gas limit for basic transactions
            gasPrice: await infuraProvider.getGasPrice() // Get current gas price from Infura
        };

        // Send the transaction
        const transaction = await wallet.sendTransaction(tx);

        console.log('Transaction sent:', 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);
    }
}

// Call the function to send the transaction
sendTransaction();

• Infura Provider: You connect to the Ethereum network using the Infura provider (infuraProvider), which allows you to interact with Ethereum nodes.
• Private Key: Replace 'YOUR_PRIVATE_KEY' with your Ethereum wallet’s private key (keep it secure).
• Recipient Address: Replace '0xRecipientEthereumAddress' with the Ethereum address you want to send Ether to.
• Gas and Fees: The gasLimit and gasPrice fields are required for sending transactions. The getGasPrice function retrieves the current gas price from the Infura node.