React & Web3 Frameworks
Integrate front-end frameworks like React with Web3 libraries to create dynamic user interfaces for DApps.
React & Web3 Frameworks is a free Web3 & DApp Development Fundamentals lesson on CoddyKit — lesson 1 of 3. You can read the complete lesson below for free — then practise it hands-on in the browser with a built-in code editor and a 24/7 AI tutor. It is part of the Web3 & DApp Development Fundamentals learning path, one of 3 lessons in the course, and your progress syncs across the web and the CoddyKit app.
DApps Need User Interfaces
Decentralized Applications (DApps) aren't just smart contracts running on a blockchain. Just like traditional apps, they need a user interface (UI) for people to interact with them.
This UI is what users see and click. It connects to their crypto wallet (like MetaMask) and communicates with the blockchain to display information or send transactions.
React for Dynamic UIs
React is a very popular JavaScript library for building modern user interfaces. It's known for its component-based architecture, where your UI is broken down into small, reusable pieces.
Using React helps developers create dynamic, responsive, and complex DApp front-ends more efficiently.
Web3 Libraries: The Blockchain Bridge
To make your React app talk to the Ethereum blockchain, you need a 'Web3 library'. These libraries act as a crucial bridge, translating your JavaScript code into blockchain-understandable commands.
- Web3.js: A comprehensive and widely used library for interacting with the Ethereum blockchain.
- Ethers.js: A modern, lightweight, and often preferred alternative to Web3.js, known for its clean API.
Setting Up a React Project
Let's start by creating a new React project. We'll use create-react-app, a common tool that sets up a new React application with a good default structure.
Open your terminal and run the following command:
npx create-react-app my-dapp-frontendInstalling a Web3 Library
After creating your React project and navigating into its directory, the next step is to install a Web3 library. For this lesson, we'll use Web3.js.
Run this command in your project's terminal:
npm install web3Connecting to an Ethereum Provider
Your DApp needs a connection to the Ethereum network. This connection is typically provided by the user's browser wallet, such as MetaMask. MetaMask injects a global window.ethereum object into the browser.
We use this window.ethereum object to initialize our Web3.js instance, allowing our app to read from and write to the blockchain.
Code Demo: Initialize Web3
This React component initializes Web3.js when the component mounts. It checks for a MetaMask provider and attempts to connect, updating the UI based on the connection status.
import React, { useEffect, useState } from 'react';
import Web3 from 'web3';
function App() {
const [web3, setWeb3] = useState(null);
const [isConnected, setIsConnected] = useState(false);
useEffect(() => {
const initWeb3 = async () => {
if (window.ethereum) {
try {
// Request account access
await window.ethereum.request({ method: 'eth_requestAccounts' });
const web3Instance = new Web3(window.ethereum);
setWeb3(web3Instance);
setIsConnected(true);
console.log('Web3 connected!');
} catch (error) {
console.error('User denied or connection error:', error);
}
} else {
console.log('MetaMask not detected. Install it!');
}
};
initWeb3();
}, []); // Runs once on component mount
return (
<div>
<h1>DApp Frontend</h1>
{isConnected ? (
<p>Connected to Ethereum!</p>
) : (
<p>Not connected. Please install MetaMask.</p>
)}
</div>
);
}
export default App;Fetching User Account Address
Once connected to the Ethereum provider, we can use our web3 instance to retrieve the user's connected wallet addresses. This is a fundamental step for any DApp that needs to display user-specific data or prepare for transactions.
We typically fetch the first account from the list returned by web3.eth.getAccounts().
Displaying Account in React State
To show the connected account address in our React application, we'll store it in React's state using the useState hook. This allows the UI to automatically update when the account is fetched.
Let's update our App.js to display the connected account:
import React, { useEffect, useState } from 'react';
import Web3 from 'web3';
function App() {
const [web3, setWeb3] = useState(null);
const [account, setAccount] = useState(null);
const [isConnected, setIsConnected] = useState(false);
useEffect(() => {
const initWeb3 = async () => {
if (window.ethereum) {
try {
await window.ethereum.request({ method: 'eth_requestAccounts' });
const web3Instance = new Web3(window.ethereum);
setWeb3(web3Instance);
setIsConnected(true);
const accounts = await web3Instance.eth.getAccounts();
setAccount(accounts[0]); // Store the first account
console.log('Connected account:', accounts[0]);
} catch (error) {
console.error('Connection error:', error);
setAccount(null);
setIsConnected(false);
}
} else {
console.log('MetaMask not detected.');
setAccount(null);
setIsConnected(false);
}
};
initWeb3();
}, []); // Empty dependency array means this runs once on mount
return (
<div>
<h1>My DApp</h1>
{isConnected && account ? (
<p>Connected account: <code>{account}</code></p>
) : (
<p>Please connect your wallet.</p>
)}
</div>
);
}
export default App;Web3 Integration Check
Which of the following is the primary purpose of a Web3 library (like Web3.js or Ethers.js) in a React DApp?
Integrating React & Web3 Recap
Today, we took our first steps into building DApp front-ends! We learned that React is excellent for building dynamic UIs, and Web3 libraries like Web3.js are crucial for connecting these UIs to the Ethereum blockchain.
We covered how to set up a React project, install Web3.js, initialize a connection using the window.ethereum provider, and fetch the user's connected wallet address to display in our app.
This foundational knowledge is key to making your DApps interactive and user-friendly. Next, we'll dive deeper into handling wallet connections and transactions.
Frequently asked questions
Is the “React & Web3 Frameworks” lesson free?
Yes — the full text of “React & Web3 Frameworks” is free to read here on the web, and the Web3 & DApp Development Fundamentals course includes 3 lessons in total. To practise it interactively (a built-in code editor and a 24/7 AI tutor) and unlock the rest of the Web3 & DApp Development Fundamentals course, upgrade to CoddyKit PRO.
What will I learn in “React & Web3 Frameworks”?
Integrate front-end frameworks like React with Web3 libraries to create dynamic user interfaces for DApps. You practise Web3 & DApp Development Fundamentals with hands-on code you run directly in the browser, and a 24/7 AI tutor answers your questions as you work through the lesson.
Do I need any experience to start Web3 & DApp Development Fundamentals?
No prior experience is required. Web3 & DApp Development Fundamentals on CoddyKit is structured for beginners through advanced learners; this is — lesson 1 of 3, so you can start here or from the beginning and move at your own pace.
How long does the “React & Web3 Frameworks” lesson take?
Most CoddyKit lessons take about 5–10 minutes. Each one is bite-sized and interactive, so you make steady progress and pick up exactly where you left off across the web and the app.
Can I write and run code in this Web3 & DApp Development Fundamentals lesson?
Yes. Every Web3 & DApp Development Fundamentals lesson includes a built-in code editor, so you write and run real code right in your browser and get instant AI feedback — no local setup required.
All lessons in this course
- React & Web3 Frameworks
- Integrating Wallets
- Handling Transactions & Events