Single Page Application concept in React - Mini Project: Build & Apply

Build a Simple Single Page Application (SPA) with React

📖 Scenario: You want to create a small website that shows different content without reloading the page. This is called a Single Page Application (SPA). You will use React to build it.

🎯 Goal: Build a React SPA with two buttons to switch between two views: Home and About. Clicking a button changes the displayed content without reloading the page.

📋 What You'll Learn

Create a React functional component called App.

Use useState to track the current page.

Add two buttons labeled Home and About.

Show different text depending on the selected page.

Switch content instantly when clicking buttons without page reload.

💡 Why This Matters

🌍 Real World

Single Page Applications are common for websites that want fast, smooth user experiences without full page reloads. React is a popular tool to build SPAs.

💼 Career

Understanding SPA basics with React is essential for frontend developer roles, enabling you to build modern interactive web apps.

1

Set up the React component and initial state

Create a React functional component called App. Inside it, use useState to create a state variable named page with the initial value 'home'.

React

import React, { useState } from 'react';

function App() {
  // Your code here
}

Hint

Remember to import useState from React and call it inside your App function.

2

Add buttons to switch pages

Inside the App component, add two <button> elements labeled Home and About. Add onClick handlers to these buttons that call setPage with 'home' and 'about' respectively.

React

import React, { useState } from 'react';

function App() {
  const [page, setPage] = useState('home');

  // Add two buttons with onClick handlers here
}

Hint

Use arrow functions inside onClick to call setPage with the correct page name.

3

Display content based on the current page

Below the buttons, add a conditional rendering that shows <p>Welcome to the Home page</p> when page is 'home', and <p>This is the About page</p> when page is 'about'. Use a JavaScript if or ternary expression inside the JSX.

React

import React, { useState } from 'react';

function App() {
  const [page, setPage] = useState('home');

  return (
    
       setPage('home')}>Home
       setPage('about')}>About
      {/* Add conditional content here */}
    
  );
}

Hint

Use a ternary operator inside curly braces to show different paragraphs based on page.

4

Add basic accessibility and semantic HTML

Wrap the buttons inside a <nav> element with an aria-label of 'Main navigation'. Wrap the content paragraph inside a <main> element.

React

import React, { useState } from 'react';

function App() {
  const [page, setPage] = useState('home');

  return (
    
      {/* Wrap buttons in nav with aria-label */}
      {/* Wrap content in main */}
    
  );
}

Hint

Use semantic HTML tags to improve accessibility and structure.

Practice

1. What is the main advantage of a Single Page Application (SPA) compared to traditional multi-page websites?

easy

A. It uses only server-side rendering without JavaScript.

B. It loads the page once and updates content dynamically without full reloads.

C. It requires a new page load for every user action.

D. It does not support navigation between different views.

Solution

1. Step 1: Understand SPA behavior

   SPAs load a single HTML page and dynamically update content without reloading the entire page.

2. Step 2: Compare with traditional websites

   Traditional sites reload the whole page on navigation, causing slower user experience.

3. Final Answer:

   It loads the page once and updates content dynamically without full reloads. -> Option B

4. Quick Check:

   SPA = dynamic content update without reload [OK]

Hint: SPAs avoid full page reloads for faster user experience [OK]

Common Mistakes:

• Thinking SPAs reload pages on every action
• Confusing SPAs with server-only rendering
• Believing SPAs don't support navigation

2. Which React library is commonly used to manage navigation and URL paths in a Single Page Application?

easy

A. Styled Components

B. Redux

C. Axios

D. React Router

Solution

1. Step 1: Identify navigation management in React

   React Router is designed to handle routing and URL paths in SPAs.

2. Step 2: Differentiate other libraries

   Redux manages state, Axios handles HTTP requests, Styled Components manage styling.

3. Final Answer:

   React Router -> Option D

4. Quick Check:

   Routing in React SPA = React Router [OK]

Hint: React Router controls SPA navigation and URLs [OK]

Common Mistakes:

• Confusing Redux with routing
• Thinking Axios manages navigation
• Assuming styling libraries handle routing

3. Given this React SPA code snippet using React Router:

import { BrowserRouter, Routes, Route } from 'react-router-dom';

function App() {
  return (
    <BrowserRouter>
      <Routes>
        <Route path='/' element=<Home /> />
        <Route path='/about' element=<About /> />
      </Routes>
    </BrowserRouter>
  );
}

What happens when the user navigates to /about URL?

medium

A. Nothing happens because routes are not defined correctly.

B. The browser reloads the entire page and shows About component.

C. The About component renders without a full page reload.

D. The Home component renders instead of About.

Solution

1. Step 1: Analyze React Router setup

   The Route with path '/about' renders the About component inside BrowserRouter.

2. Step 2: Understand SPA navigation

   React Router updates the view without reloading the whole page when navigating to '/about'.

3. Final Answer:

   The About component renders without a full page reload. -> Option C

4. Quick Check:

   React Router navigation = no full reload [OK]

Hint: React Router changes views without reloading page [OK]

Common Mistakes:

• Assuming full page reload on route change
• Thinking routes are not matched correctly
• Confusing Home and About components

4. Identify the error in this React SPA routing code:

import { BrowserRouter, Routes, Route } from 'react-router-dom';

function App() {
  return (
    <BrowserRouter>
      <Routes>
        <Route path='/' component={Home} />
        <Route path='/profile' element=<Profile /> />
      </Routes>
    </BrowserRouter>
  );
}

medium

A. The first Route uses 'component' prop instead of 'element'.

B. The BrowserRouter is missing a closing tag.

C. Routes should be replaced with Switch.

D. Profile component is not imported.

Solution

1. Step 1: Check Route props

   React Router v6 uses 'element' prop with JSX, not 'component'.

2. Step 2: Verify other code parts

   BrowserRouter is properly closed, Routes is correct in v6, and Profile import is not shown but not necessarily an error here.

3. Final Answer:

   The first Route uses 'component' prop instead of 'element'. -> Option A

4. Quick Check:

   React Router v6 Route uses element prop [OK]

Hint: Use 'element' prop with JSX in React Router v6 [OK]

Common Mistakes:

• Using 'component' prop from older React Router versions
• Confusing Routes with Switch in v6
• Assuming missing closing tags without checking

5. You want to build a React SPA that shows a loading spinner while fetching user data on route change. Which approach best fits SPA principles?

hard

A. Use React Router for routes and show a spinner component while fetching data asynchronously in the route component.

B. Reload the entire page on each route change to fetch fresh data.

C. Fetch all user data once on app load and never update it.

D. Use multiple HTML pages and link between them for each user view.

Solution

1. Step 1: Understand SPA data fetching

   SPAs fetch data asynchronously and update views without full reloads.

2. Step 2: Implement loading state in route components

   Showing a spinner while fetching data fits SPA dynamic update and user feedback.

3. Step 3: Eliminate non-SPA approaches

   Reloading pages or using multiple HTML pages breaks SPA flow; fetching once without updates is inflexible.

4. Final Answer:

   Use React Router for routes and show a spinner component while fetching data asynchronously in the route component. -> Option A

5. Quick Check:

   SPA + async data + spinner = Use React Router for routes and show a spinner component while fetching data asynchronously in the route component. [OK]

Hint: Show spinner during async fetch inside SPA route components [OK]

Common Mistakes:

• Reloading pages instead of dynamic updates
• Not showing loading feedback during fetch
• Ignoring SPA dynamic data needs