web3data-js-example-sign-txn.js

require('dotenv').config(); // Load your environment variables with 'dotenv'
const EthereumTx = require('ethereumjs-tx').Transaction;
const { privateToAddress } = require('ethereumjs-util');
const Web3Data = require("web3data-js");

const w3d = new Web3Data(process.env.API_KEY);

const TO_ADDRESS = 'YOUR_ADDRESS';
const API_KEY = 'YOUR_API_KEY'; // Need one? see amberdata.io/onboarding
const PRIV_KEY = Buffer.from('YOUR_PRIVATE_KEY', 'hex');

/**
 * Simple method that takes in a nonce and constructs the raw transaction
 * @param nonce the transaction nonce
 * @return {string} the raw transaction data
 */
const createTransactionObject = nonce => {

    // Create the transaction object
    const tx = new EthereumTx({
          nonce: nonce, // <-- Set your nonce value here (should increment for every transaction)
          gasPrice: '0xF0E95B47', // 4041825095 Wei
          gasLimit: '0x5208', // 21000 Wei
          to: TO_ADDRESS,
          value: '0x38D7EA4C68000', // 0.0001Eth | the value to send
      },
      {chain: 'rinkeby'});

    // Sign the transaction with your private key (must set private key in .env file)
    tx.sign(PRIV_KEY);

    // Serialize the transaction (convert to raw data bits) and then convert to hex
    // This is the format that the transaction must be in to send a raw transaction.
    return `0x${tx.serialize().toString('hex')}`;
};

// Derive the sender's public key (address) from the private key
const sender = '0x' + privateToAddress(PRIV_KEY).toString('hex');
 
// Send the json rpc request to get the total number of transactions of
// the sender address (this is used to select the correct nonce).
// More info about the nonce: https://kb.myetherwallet.com/en/transactions/what-is-nonce/
const nonce = await w3d.rpc("eth_getTransactionCount", [sender, "latest"]);

// Convert nonce to an int, add 1 and then convert back to hex
const rawTransaction = createTransactionObject('0x' + (parseInt(nonce) + 1).toString(16));

// Send the json rpc request to send a raw transaction with the object we just created
const transactionHash = await w3d.rpc("eth_sendRawTransaction", rawTransaction);

// Log the link to where you can view that transaction on amberdata.io
console.log(`https://ethereum-rinkeby.amberdata.io/transactions/0x${transactionHash}`);