Metamask: Web3.js – Extender and Mobile App

As a React developer building decentralized applications (dApps) on the Ethereum blockchain, you are probably familiar with the importance of secure communication between your front-end and back-end. A crucial aspect is ensuring that your contract functions are successfully called from your application.

In this article, we will look at using Metamask, a popular Web3.js extender for React applications, to call contract functions on your local Ethereum testnet or mainnet.

What is Metamask?

Metamask is an open-source browser extension that allows users to interact with the Ethereum blockchain directly in their web browsers. It provides a user-friendly interface for sending and receiving Ether (ETH) as well as interacting with various contract functions.

Why call contract functions with Metamask?

Calling contract functions on your local testnet or mainnet can be useful for testing, development, or even production deployment. However, it is important to note that calling contract functions directly from a browser extension may not work due to security and compatibility reasons.

Here are some scenarios where you might want to call contract functions with Metamask:

• Testing decentralized applications: If you are building a dApp on the Ethereum blockchain, Metamask can help you test the functionality of your application without having to set up an external network.

• Development environment

  

  : You can use Metamask to interact with local test or development networks to test contract functions before deploying them to a live chain.

• Production deployment: If you plan to deploy your dApp to the mainnet, it is essential to ensure that your contract functions are called successfully. Metamask can help you do this by providing a secure interface to interact with your contract.

Metamask Extender and Metamask Mobile App

The Metamask Extender is a lightweight browser extension that allows you to access the Ethereum blockchain in your web browser. It is available for Chrome, Firefox, Safari, and Microsoft Edge. Once installed, you can use the Metamask Extender to interact with your contract functions.

How ​​to Call Contract Functions Using Metamask

To call contract functions using Metamask, follow these steps:

• Install the Metamask Extender: Download and install the Metamask Extender from the official website.

• Open the Extender Settings: Click the three dots (⋯) next to your browser icon in the address bar, then select “Settings”.

• Select testnet or mainnet: Select the Ethereum network you want to use (e.g. Ropsten testnet or Rinkeby mainnet).

• Create new wallet: Create a new wallet or use an existing one.

• Install MetaMask Web SDK: The MetaMask extender provides a Web SDK for interacting with your contract functions. You will need to install this JavaScript library in your React application.

Here is an example of how you can call a contract function using Metamask in your React component:

“jsx

import React, { useState } from ‘react’;

import metamaskWebSdk from “@metamask/web-sdk”;

const Web3 = metamaskWebSdk;

function MyComponent() {

const [contractAddress, setContractAddress] = useState(‘0x…’);

const callFunction = async () => {

try {

// Call contract function with Metamask

const web3 = new Web3(metamaskWebSdk);

const account =await metamaskWebSdk.getAccounts().find((account) => account.address ===tractAddress);

const result = waiting web3.eth.call({ to:tractAddress, data: ‘0x…’, value: ‘0x…’ });

console.log(result); // Print the function returned by the contract

} Catch (error) {

Console.