Subscription transactions with web3.js via metamask: a step by step guide
As a developer building blockchain -based applications, you are probably familiar with the concept of interacting with blockchain. However, executing transactions programming in your web application can be a challenge. In this article, we will take you to the transaction subscription process using Web3.Js and inject the metamask functionality into your browser to facilitate safe execution of the transaction.
Prerequisites
Before proceeding, make sure:
- You have a basic understanding of JavaScript, HTML and CSS.
- You installed Node.JS and NPM (Node.JS packet manager) on your system.
- You have a blockchain-based project, including a contract implementation and a back-end server.
Step 1: Configure Metamask
Metamask is a browser extension that allows users to manage their digital assets, including private keys and wallet addresses. To use metamask with web3.js, you will need:
- Install the Metamask browser extension.
- Create a metamask account by providing your email address and creating a password.
- Activate the web3 extension in your browser settings.
Step 2: Configure Web3.js
Web3.JS is a popular JavaScript library to interact with Ethereum blockchain. To use it, you will need:
- Install Node.JS and NPM (as mentioned earlier).
- Create a new node.js project using
NPM Init.
- Initialize your project by executing
NPM Install Web3on your terminal.
- Import Web3.js in your application:
Const Web3 = Requires ('Web3').
Step 3: Inject Metamask functionality into your browser
To inject metamask functionality into your browser, you will need to:
- Create a new file called
index.htmland add the following code:
`html
Sign Transaction Using Metamask with Web3.JS
`
In this code, we are using CDN’s min.js file to import Web3.js.
Step 4: Create a script.js
file
Create a new file called script.js and add the following code:
`JavaScript
CONST Web3 = Requires (‘Web3’);
CONST Web3 = new Web3 (Window.ethereum);
Document.getelementbyid (‘Web3’). Addeventlistener (‘Input’, (e) => {
CONST PRIVATEKE = E.TARGET.VALUE;
Web3.eth accounts.add (privatekey) .then ((account) => {
Document.getelementbyid (‘response transaction’). Innerhtml = Signed transaction with account: $ {account.address};
});
});
Document.getelementbyid (‘Sign-Transaction’). Addeventlistener (‘Click’, Async () => {
to try {
CONST SIGNATURE = Wait Web3.eth.signtransaction ({
From: ‘0x … your_account_address …’, // Replace with your account address
Data: ”, // data to sign (for example, txhash, contract methods)
GASPRICE: 20, // Gas price for the transaction
});
Consta Translation Resort = Web3.eth.SENDSIGNEDTRANSATION (SIGNATURE.Rawtransaction);
document.getelementbyid (‘response transaction’). Innerhtml = Signed transaction and sent to blockchain!;
} catch (error) {
console.error (error);
}
});
`
In this code, we are using Web3.js to create a new Ethereum account using the user’s private key.
