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Use web3.js

In this tutorial, you'll send a regular transaction of 0.001 ETH from one account to another using the Web3 JavaScript library.

Prerequisites​

info

Use MetaMask or similar to create an Ethereum account for testing.

Steps​

1. Select your network and verify funds​

  • Sepolia - To use the Sepolia testnet, ensure that your account has Sepolia ETH. You can use the MetaMask faucet to add more funds.

  • Alternative network - To use an alternative network, ensure that your account has testnet ETH for that network.

    note

    When using an alternative network, you'll:

    • Update your .env file in Step 4 with the alternative network name.
    • Update the chaindId in Step 5 with the alternative network chain ID.

2. Create a project directory​

Create a new directory for your project. This can be done from the command line:

mkdir sendTransaction

Change into the new directory:

cd sendTransaction

3. Install required packages​

Install the web3 and dotenv packages in the project directory.

info

The dotenv package allows you to use a .env file to securely store private environment variables on your local machine.

Install the web3 package:

npm install web3

Install the dotenv package:

npm install dotenv --save

4. Create a .env file​

Create a .env file in your project directory to store the project and Ethereum account details.

.env
ETHEREUM_NETWORK = "<NETWORK>"
INFURA_API_KEY = "<YOUR-API-KEY>"
SIGNER_PRIVATE_KEY = "<PRIVATE-KEY>"

Replace the following values in the .env file:

  • <NETWORK> with sepolia or the alternative network you are using.
  • <YOUR-API-KEY> with your API key of the web3 project.
  • <PRIVATE-KEY> with the private key of your Ethereum account. A transaction must be signed with the sender's private key. Make sure that you prefix the SIGNER_PRIVATE_KEY value with 0x. The private key you export from MetaMask isn't prefixed with 0x.
danger

Never disclose your private key. Anyone with your private keys can steal the assets controlled by those keys.

5. Create a send.js file​

In the project directory, create a send.js file, which configures and sends the transaction. For example:

Important
  • To send test ETH to an account of your choice, update line 20 with your selected account.
  • If you are using an alternative network to Sepolia, update the chainId in line 39 with your network chain ID.
send.js
const { Web3 } = require("web3");
const { ETH_DATA_FORMAT, DEFAULT_RETURN_FORMAT } = require("web3");
async function main() {
  // Configuring the connection to an Ethereum node
  const network = process.env.ETHEREUM_NETWORK;
  const web3 = new Web3(
    new Web3.providers.HttpProvider(
      `https://${network}.infura.io/v3/${process.env.INFURA_API_KEY}`,
    ),
  );
  // Creating a signing account from a private key
  const signer = web3.eth.accounts.privateKeyToAccount(
    process.env.SIGNER_PRIVATE_KEY,
  );
  web3.eth.accounts.wallet.add(signer);
  await web3.eth
    .estimateGas(
      {
        from: signer.address,
        to: "0xAED01C776d98303eE080D25A21f0a42D94a86D9c", // Replace with your selected account
        value: web3.utils.toWei("0.0001", "ether"),
      },
      "latest",
      ETH_DATA_FORMAT,
    )
    .then((value) => {
      limit = value;
    });

  // Creating the transaction object
  const tx = {
    from: signer.address,
    to: "0xAED01C776d98303eE080D25A21f0a42D94a86D9c",
    value: web3.utils.toWei("0.0001", "ether"),
    gas: limit,
    nonce: await web3.eth.getTransactionCount(signer.address),
    maxPriorityFeePerGas: web3.utils.toWei("3", "gwei"),
    maxFeePerGas: web3.utils.toWei("90", "gwei"),
    chainId: 11155111, // If you're not using Sepolia, replace with your network chain ID
    type: 0x2,
  };
  signedTx = await web3.eth.accounts.signTransaction(tx, signer.privateKey);
  console.log("Raw transaction data: " + signedTx.rawTransaction);
  // Sending the transaction to the network
  const receipt = await web3.eth
    .sendSignedTransaction(signedTx.rawTransaction)
    .once("transactionHash", (txhash) => {
      console.log(`Mining transaction ...`);
      console.log(`https://${network}.etherscan.io/tx/${txhash}`);
    });
  // The transaction is now on chain!
  console.log(`Mined in block ${receipt.blockNumber}`);
}
require("dotenv").config();
main();

6. Execute the transaction​

To execute the transaction, run:

node send.js

The terminal displays a log similar to the following. Select the URL to view the transaction details.

Raw transaction data:
0x02f87383aa36a78084b2d05e0084b2d05e0082520894aed01c776d98303ee080d25a21f0a42d94a86d9c865af3107a400080c080a058b88e1e01517ecaab0349f838aa07cbc90297679b2bbf2f48fa6f53b02ae358a00564373fe50e923d87f1da8d7805533c71cf81af32d66b3b2f45e972e4896fde
Mining transaction ...
https://sepolia.etherscan.io/tx/0x31581c7ac2020de48d48363171fb3406f19fd14e67575695dafba51295959049
Mined in block 3773903
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