Web3.js

web3.js is a collection of libraries that allow you to interact with a local or remote Ethereum node using HTTP, IPC, or WebSocket. This guide describes how to configure Web3.js when developing Dapps using Web3 with the IoTeX Network.

Connect to the IoTeX network

// mainnet 
const web3 = new Web3('https://babel-api.mainnet.iotex.io');
// testnet
const web3 = new Web3('https://babel-api.testnet.iotex.io');

Create blockchain account

If the installation and instantiation of web3 were successful, the following should successfully return a random account:

const account = web3.eth.accounts.create();

Import a private key

If you have backup the private key of your account, you can restore your account.

const account = web3.eth.accounts.privateKeyToAccount(privateKey)

Example: Get Balance

Initialize a new nodejs app:

mkdir Web3Test
cd Web3Test
npm init -y
npm install web3 big.js -s

then edit index.js as below:

// index.js

const Web3 = require('web3');
const Big = require('big.js');

// Initialize web3.js using the IoTeX Babel endpoint
const web3 = new Web3(new Web3.providers.HttpProvider("https://babel-api.testnet.iotex.io"));

// Create a brand new account
const account = web3.eth.accounts.create();
console.log("Account created: %s", account.address);

// Query the balance of the IoTeX address io1qz02qneamgdseprun3eswcudg2runs4kwpv842
// You can use "ioctl account ethaddr <address>" to convert to Eth address format:
let address = "0x009EA04f3dda1b0C847c9C7307638d4287c9C2B6"
web3.eth.getBalance(address).then(
    function (balance) {
        let iotxBalance = Big(balance).div(10**18);
        console.log("Balance of %s is %s IOTX",address,iotxBalance.toFixed(18))
    });  

Run the example:

node index.js

Example: Transfer IOTX tokens

The following example shows how to use Web3Js to send an IOTX token transfer to another wallet. Please notice the txConfig object:

const Web3 = require('web3');
const HDWalletProvider = require('truffle-hdwallet-provider');

// Web3 - Accounts private keys
const privateKeys = [
    "<set a private key here>",
    "<set a private key here>",
    "<set a private key here>"
  ];

// Interact with the IoTeX testnet
const ENDPOINT= "https://babel-api.testnet.iotex.io";
// Uncomment the line below to interact with the IoTeX mainnet
// const ENDPOINT= "https://babel-api.mainnet.iotex.io";

// Instantiate the accounts provider
const provider = new HDWalletProvider(privateKeys, ENDPOINT, 0, 3);

// Instantiate the Web3 object
const web3 = new Web3(provider);

(async () => {

  // Check that Web3 is connected
  await web3.eth.net.isListening();
  console.log('Web3 is connected.');
  // Get the ChainId (IoTeX will return 4689 for mainnet and 4690 
  // for testnet). See below.
  const chainId = await web3.eth.net.getId();
  
  // Get the accounts
  let accounts = await web3.eth.getAccounts();
  console.log(`accounts: ${JSON.stringify(accounts)}`);
  
  // Configure the transfer settings
  let txConfig = {
    from: accounts[2],
    to: accounts[1],
    // notice we use a slightly higher gas limit than Ethereum default 
    // so we set it explicitely.
    gasPrice: "1000000000000",
    gas: "85000",
    value: "10000000000000000",  // Sending 0.01 IOTX
    // IoTeX also has a different Chain Id than the Etehreum networks
    // that's why queried it above
    chainId
  };

  // Sign the tx
  let signedTx = await web3.eth.signTransaction(txConfig, accounts[2]);
  console.log("Raw signed Tx: ", signedTx.raw);

  // Calculate the expected Hash
  const txHash = await web3.utils.sha3(signedTx.raw);
  console.log("Tx Hash (calculated): ",txHash);

  // Send the transaction
  web3.eth.sendSignedTransaction(signedTx.raw)
  .on("receipt", function(receipt) {
    console.log("Tx Hash (Receipt): ", receipt.transactionHash);
  })
  .on("error", function(e) { console.log(e); });

})();