Interact with a contract function using Web3.js

Question

I finished testing my smart contract functionality with "unlocked accounts" (which don't require complex signing) on a local dev blockchain, but now I would like to deploy on MAINNET and use private keys.

After I deploy, I want to interact with a function in my smart contract using Web3.js, but all the tutorials I've seen use "unlocked accounts" on private local chains which unfortunately aren't helping. What do I have to add to this contract instance in order to broadcast real signed transactions that are valid and will invoke functions on MAINNET.

const Web3 = require('web3');
const myContract = require('./build/contracts/myContract.json');   //because I use Truffle

const init = async () => {
    const web3 = new Web3('https://mainnet.infura.io/v3/MY-INFURA-ID');
    const id = await web3.wth.net.getId();
    const deployedNetwork = myContract.networks[id];
    const contract = new web3.eth.Contract(
        myContract.abi,
        deployedNetwork.address
    );
}

//I have the HDwallets package if that's relevant..

Help would be really really appreciated, I'm lost!

Answer 1

You can use HDWallet Provider.

const Web3 = require('web3');
const myContract = require('./build/contracts/myContract.json');
const HDWalletProvider = require("@truffle/hdwallet-provider");

const mnemonicPhrase = 'country roads take home ....';

const init = async () => {
    const provider = new HDWalletProvider({
        mnemonic: {
            phrase: mnemonicPhrase
        },
        providerOrUrl: 'https://mainnet.infura.io/v3/MY-INFURA-ID',
    });

    const web3 = new Web3(provider);
    const id = await web3.eth.net.getId();
    const deployedNetwork = myContract.networks[id];

    const contract = new web3.eth.Contract(
        myContract.abi,
        deployedNetwork.address
    );
}