base-react-app

Base React App

React application used as the base structure for all projects in this guide.

Tech Stack

Package	Version
React	19.2.3
React DOM	19.2.3
React Scripts	5.0.1
Testing Library	16.3.1

Setup

# Install dependencies
npm install

# Start development server
npm start

# Create production build
npm run build

# Run tests
npm test

• File Structure
• Code Breakdown
• App Usage

File Structure

base-react-app/
├── public/
    ├── index.html
    ├── favicon.ico
    ├── manifest.json
    └── robots.txt
├── src/
    ├── assets/
    |   ├── images/
    |   |   ├── basic.jpg
    ├── components/
    |   ├── UI/
    |   |   ├── Card.css
    |   |   ├── Card.js
    |   ├── Footer.css
    |   ├── Footer.js
    |   ├── Header.css
    |   ├── Header.js
    ├── App.js
    ├── index.css
    ├── index.js
├── .gitignore
├── package.json
├── readme.md

Code Breakdown

The index.js file:

// import React from 'react';
import ReactDOM from 'react-dom/client';

import './index.css';
import App from './App';

const root = ReactDOM.createRoot(document.getElementById('root'));
root.render(<App />);

// import React from 'react';

• Imports the core React library, which is needed to use JSX (JavaScript XML) and create React components.
• Starting from release 17, however, you no longer need this statement.

import ReactDOM from 'react-dom/client';

• ReactDOM is a library that interacts with the DOM to render React components.
• react-dom/client is a new way (starting from React 18) to manage rendering in React apps, replacing ReactDOM.render

import './index.css';

• Imports the global CSS file for the app.

import App from './App';

• Imports the App component from App.js, which serves as the root component of the application.
• The App component is typically where the main structure and logic of the app reside.

const root = ReactDOM.createRoot(document.getElementById('root'));

• This selects the root DOM element with the id="root" (defined in public/index.html) and creates a React root using ReactDOM.createRoot.
• The root serves as the entry point for the React application, allowing React to manage the DOM within this element.
• In the index.html file, this is the target DOM element where the entire React app will be mounted:

  <div id="root"></div>

root.render(<App />);

• Renders the App component inside the root element in the DOM.
• The <App /> syntax is JSX, representing a React component.

The summary, the index.js component:

1. Sets up the environment.
2. Renders the top-level App component into the root DOM element.

---

The App.js file:

function App() {
  return (
    <div>
      <h2>Let's get started!</h2>
    </div>
  );
}

export default App;

function App()

• Defines a functional component called App.
• A functional component is one of the simplest ways to define a React component. It is essentially a JavaScript function that returns JSX (HTML-like syntax).

return ( ... )

• The return statement specifies what the App component renders on the screen.
• In this case, it returns a <div> element containing an <h2> element.

<div> and <h2>

• These are JSX elements that look similar to HTML but are actually JavaScript objects under the hood.
• JSX allows you to write markup directly within your JavaScript code and is then transformed into React elements during compilation.

export default App;

• This exports the App component as the default export of the file.
• Allows other files to import App (in index.js as import App from './App';) and use it in the application.
• In a larger app, the App component would usually serve as the container for other components, managing and rendering their content.

In summary, the App.js component:

1. Defines a simple functional React component.
2. Renders an HTML structure using JSX.
3. Is exported for use as the root component of the app.

Tip

Check out the React app usage documentation for information on basic app usage in this project.

 
 Back to Top