I have tried to deploy a SmartContract from web3.js node library, I am getting a transaction hash from it but how would I get the contract address after It's been mined by a miner? here is my code

const Web3 = require('web3');
const Tx = require('ethereumjs-tx');
const provider = new Web3.providers.HttpProvider("https://ropsten.infura.io/v3/<Api key>");
const web3 = new Web3(provider);

const account1 = '<acc address>';
web3.eth.defaultAccount = account1;

const privateKey1 = Buffer.from('<private key here>', 'hex');

const myData = "<data here>"

web3.eth.getTransactionCount(account1, (err, txCount) => {
// Build the transaction
  const txObject = {
    nonce:    web3.utils.toHex(txCount),
    gasLimit: web3.utils.toHex(4700000),
    gasPrice: web3.utils.toHex(web3.utils.toWei('10', 'gwei')),
    data: myData  
    // Sign the transaction
    const tx = new Tx(txObject);

    const serializedTx = tx.serialize();
    const raw = '0x' + serializedTx.toString('hex');

    // Broadcast the transaction
   web3.eth.sendSignedTransaction(raw, (err, tx) => {

2 Answers 2


The callback is returning the transaction hash. Instead, I suggest you to use "promise" or ".on" to get the receipt as documented in the package document https://web3js.readthedocs.io/en/1.0/web3-eth.html#sendsignedtransaction

It would look like something like:

// Broadcast the transaction
.on('receipt', console.log);


// Broadcast the transaction
.then(receipt => console.log(receipt);

You may want to consider the following alternative for deploying a contract (tested with web3 v1.0.0-beta.34):

async function deploy(contractName, contractArgs) {
    const abi = fs.readFileSync(YOUR_ARTIFACTS_PATH + contractName + ".abi");
    const bin = fs.readFileSync(YOUR_ARTIFACTS_PATH + contractName + ".bin");
    const contract = new web3.eth.Contract(JSON.parse(abi));
    const options = {data: "0x" + bin, arguments: contractArgs};
    const transaction = contract.deploy(options);
    const handle = await send(transaction);
    const args = transaction.encodeABI().slice(options.data.length);
    return new web3.eth.Contract(JSON.parse(abi), handle.contractAddress);

async function send(transaction) {
    const options = {
        to   : transaction._parent._address,
        data : transaction.encodeABI(),
        gas  : (await util.web3.eth.getBlock("latest")).gasLimit
    const signedTransaction  = await web3.eth.accounts.signTransaction(options, YOUR_PRIVATE_KEY);
    const transactionReceipt = await web3.eth.sendSignedTransaction(signedTransaction.rawTransaction);
    return transactionReceipt;

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