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Transactions

This guide provides insights into sending transactions using web3.js, covering various scenarios from utilizing a local wallet to sending raw transactions.

Transaction Type 0 (Legacy)​

A Legacy Transaction refers to a transaction that was created using an older version of Ethereum's transaction format, also known as "transaction type 0". This transaction format was used before the EIP-1559 upgrade, which was implemented in August 2021.

import { Web3 } from"web3";

const web3 = new Web3("https://rpc2.sepolia.org");

async function txLegacy() {
  const wallet = web3.eth.wallet.add("YOUR_PRIVATE_KEY"); //make sure you have funds

  const sender = wallet[0].address;
  const recipient = "0x807BFe4940016B5a7FdA19482042917B02e68359";
  const value = 1; //wei
  const nonce = await web3.eth.getTransactionCount(sender);
  const gas = 21000;
  const gasPrice = await web3.eth.getGasPrice();

  const tx = {
    from: sender,
    to: recipient,
    value,
    nonce,
    gas,
    gasPrice,
  };

  const txReceipt = await web3.eth.sendTransaction(tx);
  console.log("Tx hash", txReceipt.transactionHash);
}

txLegacy();

Transaction Type 1 (EIP-2930)​

This EIP was introduced in April 2021, it introduces a feature called 'Transaction Type and Access List.' This improvement allows saving gas on cross-contract calls by declaring in advance which contract and storage slots will be accessed.

import { Web3 } from"web3";

const web3 = new Web3("https://rpc2.sepolia.org");

async function txEIP2930() {
  const wallet = web3.eth.wallet.add("YOUR_PRIVATE_KEY");

  const sender = wallet[0].address;
  const contractAddress1 = "0x...";
  const contractAddress2 = "0x..."
  const nonce = await web3.eth.getTransactionCount(sender);
  const gas = 500000; //could be higher
  const gasPrice = await web3.eth.getGasPrice();

  const tx = {
    from: sender,
    to: contractAddress1, //the contract we are calling
    data: "0x...",
    gas,
    gasPrice,
    type: 1,
    accessList: [
      {
        address: contractAddress2, //contract1 is calling contract2
        storageKeys: [
          "0x0000000000000000000000000000000000000000000000000000000000000000",
          "0x0000000000000000000000000000000000000000000000000000000000000001",
        ],
      },
    ],
  };


  const txReceipt = await web3.eth.sendTransaction(tx);
  console.log("Tx hash", txReceipt.transactionHash);
}

txEIP2930()

Transaction Type 2 (EIP-1559)​

When a user creates an EIP-1559 transaction, they specify the maximum fee they are willing to pay maxFeePerGas as well as a tip maxPriorityFeePerGas to incentivize the miner. The actual fee paid by the user is then determined by the network based on the current demand for block space and the priority of the transaction.

import { Web3 } from"web3";

const web3 = new Web3("https://rpc2.sepolia.org");

async function txEIP1559() {
  const wallet = web3.eth.wallet.add("YOUR_PRIVATE_KEY"); //make sure you have funds

  const sender = wallet[0].address;
  const recipient = "0x807BFe4940016B5a7FdA19482042917B02e68359";
  const value = 1; //wei
  const nonce = await web3.eth.getTransactionCount(sender);
  const gasLimit = 21000;
  const maxFeePerGas = Number((await web3.eth.calculateFeeData()).maxFeePerGas);
  const maxPriorityFeePerGas = Number((await web3.eth.calculateFeeData()).maxPriorityFeePerGas);

  const tx = {
    from: sender,
    to: recipient,
    value,
    nonce,
    gasLimit,
    maxFeePerGas,
    maxPriorityFeePerGas,
  };

  const txReceipt = await web3.eth.sendTransaction(tx);
  console.log("Tx hash", txReceipt.transactionHash);
}

txEIP1559();

Sending transactions with a local wallet​

The simplest way to sign and send transactions is using a local wallet:

// 1st step: initialize `web3` instance
import { Web3 } from 'web3';

const web3 = new Web3(/* PROVIDER*/);

// 2nd step: add an account to wallet
const privateKey = '0x7b907534ec13b19c67c2a738fdaa69014298c71f2221d7e5dec280232e996610';
const account = web3.eth.accounts.wallet.add(privateKey).get(0);
// Make sure the account has enough eth on balance to send the transaction

// 3rd step: sign and send the transaction
// Magic happens inside sendTransaction. If a transaction is sent from an account that exists in a wallet, it will be automatically signed using that account.
const receipt = await web3.eth.sendTransaction({
  from: account?.address,
  to: '0xe4beef667408b99053dc147ed19592ada0d77f59',
  value: '0x1',
  gas: '300000',
  // other transaction's params
});

Sending a raw transaction​

import { Web3 } from 'web3';

// 1st - initialize the provider
const web3 = new Web3('https://ethereum-sepolia.publicnode.com');

// 2nd - create an account
const account = web3.eth.accounts.privateKeyToAccount('0x4651f9c219fc6401fe0b3f82129467c717012287ccb61950d2a8ede0687857ba');

// 3rd - create a raw transaction object
const rawTransaction = {
  from: account.address,
  to: '0x5875da5854c2adadbc1a7a448b5b2a09b26baff8', //random wallet or contract address
  value: 1, //optional - value in wei
  maxFeePerGas: Number((await web3.eth.calculateFeeData()).maxFeePerGas),
  maxPriorityFeePerGas: Number((await web3.eth.calculateFeeData()).maxPriorityFeePerGas),
  gasLimit: 2000000
  nonce: await web3.eth.getTransactionCount(account.address), //optional - get the current nonce of the account 
  data: "0x0" //optional - encoded function signature and arguments 
};

// 4th - sign the raw transaction with the private key
const signedTransaction = await web3.eth.accounts.signTransaction(rawTransaction, account.privateKey);

// 5th - send the signed transaction
const txReceipt = await web3.eth.sendSignedTransaction(signedTransaction.rawTransaction);

console.log('Transaction Receipt:', txReceipt);
/* ↳
Transaction Receipt: {
  blockHash: '0xd73a824348ebb8c1895fbe7b2c506c287cfaadc8104628a140e7b39d7e41d50f',
  blockNumber: 4972805n,
  cumulativeGasUsed: 15266381n,
  effectiveGasPrice: 118637814298n,
  from: '0xa3286628134bad128faeef82f44e99aa64085c94',
  gasUsed: 21000n,
  logs: [],
  logsBloom: '0x00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000',
  status: 1n,
  to: '0x5875da5854c2adadbc1a7a448b5b2a09b26baff8',
  transactionHash: '0x247e4540f9b399655da90e8a0c3d9ec165f62a304f6364f45518a4d6a531cd36',
  transactionIndex: 156n,
  type: 0n
}
*/

Sending a transaction with Browser Injection (Metamask)​

This is an example html file that will send a transaction when the button element is clicked.

To run this example you'll need Metamask, the index.html file below in your folder and you'll need a local server:

npm i http-server
npx http-server

Afterwards your file will be served on a local port, which will usually be on http://127.0.0.1:8080

<!DOCTYPE html>
<html lang='en'>
  <head>
    <meta charset='UTF-8' />
    <meta name='viewport' content='width=device-width, initial-scale=1.0' />
    <title>Send Transaction Example</title>
    <script src='https://cdn.jsdelivr.net/npm/web3@4.3.0/+esm'></script>
  </head>

  <body>
    <button id='sendButton'>Send Transaction</button>
    <script>
      // Wrap the code inside an async function
      (async function () {
        try {
          // Check if MetaMask is installed and connected
          if (typeof window.ethereum === 'undefined') {
            throw new Error('MetaMask is not installed or not properly configured');
          }

          // Connect to the Ethereum network using MetaMask
          const accounts = await window.ethereum.request({ method: 'eth_requestAccounts' });

          const web3 = new Web3(window.ethereum);

          // Add event listener to the Send Transaction button
          const sendButton = document.getElementById('sendButton');
          sendButton.addEventListener('click', async () => {
            try {
              await web3.eth.sendTransaction({ from: accounts[0], to: '0x38E2fb54587208f29B1452Bb8136d271BE0912EF' });
            } catch (error) {
              console.error(error);
            }
          });
        } catch (error) {
          console.error(error);
        }
      })();
    </script>
  </body>
</html>

Contract Deployment​

Deploy a contract
// 1st step: initialize `web3` instance
import { Web3 } from 'web3';

const web3 = new Web3(/* PROVIDER*/);

// 2nd step: add an account to wallet
const privateKey = '0x7b907534ec13b19c67c2a738fdaa69014298c71f2221d7e5dec280232e996610';
const account = web3.eth.accounts.wallet.add(privateKey).get(0);
// Make sure the account has enough eth on balance to send the transaction

// fill ContractAbi and ContractBytecode with your contract's abi and bytecode

async function deploy() {
  // 3rd step: sign and send the transaction
  // In any function where you can pass from the address set address of the account that exists in a wallet, it will be automatically signed.

  try {
    // deploy
    const contract = new web3.eth.Contract(ContractAbi);
    const contractDeployed = await contract
      .deploy({
        input: ContractBytecode,
        arguments: ['Constructor param1', 'Constructor param2'],
      })
      .send({
        from: account?.address,
        gas: '1000000',
        // other transaction's params
      });

    // call method
    await contractDeployed.methods.transfer('0xe2597eb05cf9a87eb1309e86750c903ec38e527e', '0x1').send({
      from: account?.address,
      gas: '1000000',
      // other transaction's params
    });
  } catch (error) {
    // catch transaction error
    console.error(error);
  }
}

(async () => {
  await deploy();
})();

Interacting with contract methods​

Interact with contracts using a wallet under the hood
// 1st step: initialize `web3` instance
import { Web3 } from 'web3';

const web3 = new Web3(/* PROVIDER*/);

// 2nd step: add an account to wallet
const privateKeyString = '0x4651f9c219fc6401fe0b3f82129467c717012287ccb61950d2a8ede0687857ba';

const wallet = web3.eth.accounts.wallet.add(privateKeyString);
// Make sure the account has enough eth on balance to send the transaction

async function contractMethod() {
  try {
    // 3rd step: instantiate the contract with the ABI and contract address
    const myContract = new web3.eth.Contract(ABI, CONTRACT_ADDRESS);

    // 4th step: call contract method and send the tx
    await myContract.methods.doSomething().send({
      from: wallet[0].address,
      gas: '1000000',
      // other transaction's params
    });
  } catch (error) {
    // catch transaction error
    console.error(error);
  }
}

(async () => {
  await contractMethod();
})();

Sending a transaction and listening to the events​

Transactions with Web3PromiEvent
import { Web3 } from 'web3';

// 1st - initialize the provider
const web3 = new Web3(/* PROVIDER*/);

// 2nd - add an account to wallet
const privateKey = '0x4651f9c219fc6401fe0b3f82129467c717012287ccb61950d2a8ede0687857ba';
const account = web3.eth.accounts.wallet.add(privateKey).get(0);
// Make sure the account has enough eth on balance to send the transaction

// 3rd - sign and send the transaction
// Magic happens behind sendTransaction. If a transaction is sent from an account that exists in a wallet, it will be automatically signed.
const transaction = web3.eth.sendTransaction({
  from: account?.address,
  to: '0xe4beef667408b99053dc147ed19592ada0d77f59',
  value: '0x1',
  gas: '300000',
  // other transaction's params
});

// 4th - listen to the transaction events
transaction
  .on('sending', (sending) => {
    // Sending example
    console.log('Sending:', sending);
  })
  .on('sent', (sent) => {
    // Sent example
    console.log('Sent:', sent);
  })
  .on('transactionHash', (transactionHash) => {
    // Transaction hash example
    console.log('Transaction Hash:', transactionHash);
  })
  .on('confirmation', (confirmation) => {
    // Confirmation example
    console.log('Confirmation:', confirmation);
  })
  .on('error', (error) => {
    // Error example
    console.error('Error:', error);
  });
/* ↳
Sending: {
  from: '0xA3286628134baD128faeef82F44e99AA64085C94',
  to: '0xe4beef667408b99053dc147ed19592ada0d77f59',
  value: '0x1',
  gas: '0x493e0',
  gasPrice: undefined,
  maxPriorityFeePerGas: '0x9502f900',
  maxFeePerGas: '0x2b53cf7960'
}
Sent: {
  from: '0xA3286628134baD128faeef82F44e99AA64085C94',
  to: '0xe4beef667408b99053dc147ed19592ada0d77f59',
  value: '0x1',
  gas: '0x493e0',
  gasPrice: undefined,
  maxPriorityFeePerGas: '0x9502f900',
  maxFeePerGas: '0x2b53cf7960'
}
Transaction Hash: 0xa7493bc3eb6e7f41b54291cfd19d90111e68ea2cd9718da937ca4dcc1f831dde
Receipt: {
  blockHash: '0xe049c2cd2a473dad2af5ccf40c2df788cd42a237616cc84cc3861937f1aa2195',
  blockNumber: 4972912n,
  cumulativeGasUsed: 1018070n,
  effectiveGasPrice: 100635626363n,
  from: '0xa3286628134bad128faeef82f44e99aa64085c94',
  gasUsed: 21000n,
  logs: [],
  logsBloom: '0x...00',
  status: 1n,
  to: '0xe4beef667408b99053dc147ed19592ada0d77f59',
  transactionHash: '0xa7493bc3eb6e7f41b54291cfd19d90111e68ea2cd9718da937ca4dcc1f831dde',
  transactionIndex: 15n,
  type: 2n
}
Confirmation: {
  confirmations: 1n,
  receipt: {
    blockHash: '0xe049c2cd2a473dad2af5ccf40c2df788cd42a237616cc84cc3861937f1aa2195',
    blockNumber: 4972912n,
    cumulativeGasUsed: 1018070n,
    effectiveGasPrice: 100635626363n,
    from: '0xa3286628134bad128faeef82f44e99aa64085c94',
    gasUsed: 21000n,
    logs: [],
    logsBloom: '0x...000',
    status: 1n,
    to: '0xe4beef667408b99053dc147ed19592ada0d77f59',
    transactionHash: '0xa7493bc3eb6e7f41b54291cfd19d90111e68ea2cd9718da937ca4dcc1f831dde',
    transactionIndex: 15n,
    type: 2n
  },
  latestBlockHash: '0xe049c2cd2a473dad2af5ccf40c2df788cd42a237616cc84cc3861937f1aa2195'
}
Confirmation: {
  confirmations: 2n,
  receipt: {...},
  latestBlockHash: '0xf20261fc59d059c9dfd048e44c7fe1499d45822d9fe804bca70ac56559b54b1b'
}
Confirmation: {
  confirmations: 3n,
  receipt: {...},
  latestBlockHash: '0xb52380054ad2382620615ba7b7b40638021d85c5904a402cd11d00fd4db9fba9'
}
*/