Send a transaction with Polygon

As with Ethereum, transactions are state-changing actions on the Polygon PoS blockchain. Examples of transactions are:
Regular transactions from one account to another.
Contract deployment transactions, or calling a function in a smart contract.
This tutorial uses the Ethereum Web3 JavaScript library to send a transaction between two accounts on the Polygon-Mumbai testnet.
You can also use Infura Transactions (ITX) to send transactions on Polygon Mainnet. ITX is not supported on the Polygon Mumbai testnet.
Prerequisites
An Infura Web3 project with the Polygon PoS add-on​
​Node.js installed​
​MetaMask installed and an account for testing purposes
You can use MetaMask or a similar Ethereum wallet to create an account for testing purposes on the Polygon blockchain.
Steps
1. Add Polygon network to MetaMask
Refer to the Polygon instruction to add the Polygon networks to MetaMask. This tutorial uses the Polygon-Mumbai network.
2. Fund your account
​Use the Polygon faucet to load testnet MATIC on your account for the Mumbai network.
3. 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
4. Install required packages
Install the web3 and dotenv packages in the project directory.
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
5. Create the .env file
Create a .env file in your project directory to store the project and account details.
POLYGON_NETWORK = "polygon-mumbai"
INFURA_API_KEY = "<API-Key>"
SIGNER_PRIVATE_KEY = "<Private-Key>"
Ensure you replace the following values in the .env file:
<API-Key> with the API key from your Infura dashboard.
<Private-Key> with the private key of your account.
Never disclose your private key. Anyone with your private keys can steal any assets held in your account.
6. Create send.js file
In this example we'll create a JavaScript file (send.js) in the project directory which configures and sends the transaction.
const Web3 = require("web3");
​
async function main() {
  // Configuring the connection to the Polygon node
  const network = process.env.POLYGON_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);
  // Creating the transaction object
  const tx = {
    from: signer.address,
    to: "0xeAD9C93b79Ae7C1591b1FB5323BD777E86e150d4",
    value: web3.utils.toWei("0.001"),
  };
  // Assigning the right amount of gas
  tx.gas = await web3.eth.estimateGas(tx);
​
  // Sending the transaction to the network
  const receipt = await web3.eth
    .sendTransaction(tx)
    .once("transactionHash", (txhash) => {
      console.log(`Mining transaction ...`);
      console.log(`Transaction hash: ${txhash}`);
    });
  // The transaction is now on chain!
  console.log(`Mined in block ${receipt.blockNumber}`);
}
​
require("dotenv").config();
main();
7. Execute the transaction
To execute the transaction, run:
node sendTx.js
The command line will display a link to view the transaction details.
8. View the transaction details
Copy transaction hash and view the transaction in the Polygon Mumbai block explorer.

Last modified 9mo ago

Send a transaction with Polygon

Prerequisites

Steps

1. Add Polygon network to MetaMask

2. Fund your account

3. Create a project directory

4. Install required packages

5. Create the `.env` file

6. Create `send.js` file

7. Execute the transaction

8. View the transaction details