Transactions

In this tutorial, we will explore how to send different types of transactions using web3.js, focusing on Ethereum's evolving transaction formats. We'll start with legacy transactions (Transaction Type 0). Next, we'll delve into Transaction Type 1 (EIP-2930), which introduces access lists to optimize gas usage. Finally, we'll cover Transaction Type 2 (EIP-1559), the current default, which allows users to specify maximum fees and priority tips for more efficient and cost-effective transactions. Each section will include practical code examples to demonstrate sending raw transactions and interacting with ERC20 tokens on the Sepolia test network

note

Web3.js uses transaction type 2 by default

Transaction Type 0 (Legacy)

Raw Transaction

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"); // RPC node url

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,
    type: 0,
  };

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

txLegacy();

ERC20 Interaction

import { Web3 } from "web3";

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

//WETH token in Sepolia https://sepolia.etherscan.io/address/0xfff9976782d46cc05630d1f6ebab18b2324d6b14#code
const ADDRESS_WETH_SEPOLIA = "0xfFf9976782d46CC05630D1f6eBAb18b2324d6B14";
const ABI = [
  {
    constant: false,
    inputs: [
      {
        name: "dst",
        type: "address",
      },
      {
        name: "wad",
        type: "uint256",
      },
    ],
    name: "transfer",
    outputs: [
      {
        name: "",
        type: "bool",
      },
    ],
    payable: false,
    stateMutability: "nonpayable",
    type: "function",
  },
];

async function transfer() {
  //initialize wallet
  const wallet = web3.eth.accounts.wallet.add("YOUR_PRIVATE_KEY"); //make sure you have WETH tokens in the Sepolia network
  //you can swap Sepolia tokens for WETH here https://app.uniswap.org/swap?chain=sepolia

  //initialize WETH contract in sepolia
  const myERC20 = new web3.eth.Contract(ABI, ADDRESS_WETH_SEPOLIA);

  const TO = "0xEA9eEca67682Cd9c6Ce3DdD1681049D7A897289F"; //address to send the tokens to
  const VALUE = 1; //wei value, dont forget to multiply by decimals

  //send transfer and specify the type
  const txReceipt = await myERC20.methods.transfer(TO, VALUE).send({
    from: wallet[0].address,
    type: 0,
  });

  console.log(txReceipt.transactionHash);
  //=> 0x5f2087c22166f3a1909c40ce537dd564dc3d4c70c5be02f35c6406a628123b16
}

transfer();

Transaction Type 1 (EIP-2930)

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

Raw Transaction

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 gas = 500000; //could be higher
  const gasPrice = await web3.eth.getGasPrice();
  const data = "0x9a67c8b100000000000000000000000000000000000000000000000000000000000004d0"


  //create access list using web3.eth
  const accessListData = await web3.eth.createAccessList({
    from: sender,
    to: contractAddress1,
    data,
  });

  console.log(accessListData)
  /* 
  => 
  {
  "accessList": [
      {
        "address": "0x15859bdf5aff2080a9968f6a410361e9598df62f",
        "storageKeys": [
          "0x0000000000000000000000000000000000000000000000000000000000000000"
        ]
      }
    ],
    "gasUsed": "0x7671"
  }
  */

  const tx = {
    from: sender,
    to: contractAddress1, //the contract we are calling
    data,
    gas,
    gasPrice,
    type: 1,
    accessList: accessListData.accessList //access the object `accessList`
  };

  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.

Raw 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,
    type: 2,
  };

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

txEIP1559();

ERC20 Interaction

import { Web3 } from "web3";

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

//WETH token in Sepolia https://sepolia.etherscan.io/address/0xfff9976782d46cc05630d1f6ebab18b2324d6b14#code
const ADDRESS_WETH_SEPOLIA = "0xfFf9976782d46CC05630D1f6eBAb18b2324d6B14";
const ABI = [
  {
    constant: false,
    inputs: [
      {
        name: "dst",
        type: "address",
      },
      {
        name: "wad",
        type: "uint256",
      },
    ],
    name: "transfer",
    outputs: [
      {
        name: "",
        type: "bool",
      },
    ],
    payable: false,
    stateMutability: "nonpayable",
    type: "function",
  },
];

async function transfer() {
  //initialize wallet
  const wallet = web3.eth.accounts.wallet.add("YOUR_PRIVATE_KEY"); //make sure you have WETH tokens in the Sepolia network
  //you can swap Sepolia tokens for WETH here https://app.uniswap.org/swap?chain=sepolia

  //initialize WETH contract in sepolia
  const myERC20 = new web3.eth.Contract(ABI, ADDRESS_WETH_SEPOLIA);

  const TO = "0xEA9eEca67682Cd9c6Ce3DdD1681049D7A897289F"; //address to send the tokens to
  const VALUE = 1; //wei value, dont forget to multiply by decimals

  //send transfer and specify the type
  const txReceipt = await myERC20.methods.transfer(TO, VALUE).send({
    from: wallet[0].address,
    type: 2,
  });

  console.log(txReceipt.transactionHash);
  //=> 0x174bc88023be4af431fad1693a59f7a41135238510cdcd00f15f6409b5471d77
}

transfer();