Navigation links in React - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ component_behavior

intermediate

What is the output of this React navigation component?

Consider this React component that renders navigation links. What will be displayed in the browser?

React

import React from 'react';
import { Link } from 'react-router-dom';

export default function Nav() {
  return (
    <nav aria-label="Main navigation">
      <ul>
        <li><Link to="/home">Home</Link></li>
        <li><Link to="/about">About</Link></li>
        <li><Link to="/contact">Contact</Link></li>
      </ul>
    </nav>
  );
}

A A navigation bar with three clickable links labeled Home, About, and Contact.

B A navigation bar with three links but only Home and About are clickable; Contact is plain text.

C An error because Link components require an href attribute instead of to.

D Nothing renders because the component is missing a return statement.

💡 Hint

Remember that React Router's Link uses 'to' for navigation paths.

The component uses React Router's Link with 'to' attributes correctly. It renders a nav with three clickable links labeled Home, About, and Contact.

❓ state_output

intermediate

What is the active link after clicking?

This React component highlights the active navigation link. After clicking the About link, what is the value of the active state?

React

import React, { useState } from 'react';

export default function Nav() {
  const [active, setActive] = useState('Home');

  return (
    <nav aria-label="Main navigation">
      <ul>
        <li>
          <button onClick={() => setActive('Home')} aria-current={active === 'Home' ? 'page' : undefined}>Home</button>
        </li>
        <li>
          <button onClick={() => setActive('About')} aria-current={active === 'About' ? 'page' : undefined}>About</button>
        </li>
        <li>
          <button onClick={() => setActive('Contact')} aria-current={active === 'Contact' ? 'page' : undefined}>Contact</button>
        </li>
      </ul>
    </nav>
  );
}

A "Contact"

B "Home"

C "About"

D undefined

💡 Hint

Clicking the About button triggers setActive with 'About'.

The state 'active' starts as 'Home'. Clicking the About button calls setActive('About'), so active becomes 'About'.

📝 Syntax

advanced

Which option causes a syntax error in this React navigation code?

Identify which code snippet will cause a syntax error when used in a React component rendering navigation links.

React

function Nav() {
  return (
    <nav>
      <ul>
        <li><a href="/home">Home</a></li>
        <li><a href="/about">About</a></li>
        <li><a href="/contact">Contact</a></li>
      </ul>
    </nav>
  );
}

A return <nav><ul><li><a href="/home">Home</a></li><li><a href="/about">About</a></li><li><a href="/contact">Contact</a></li></ul></nav>;

B return (<nav><ul><li><a href="/home">Home</a><li><a href="/about">About</a></li><li><a href="/contact">Contact</a></li></ul></nav>);

C ;)>van/<>lu/<>il/<>a/<tcatnoC>"tcatnoc/"=ferh a<>il<>il/<>a/<tuobA>"tuoba/"=ferh a<>il<>il/<>a/<emoH>"emoh/"=ferh a<>il<>lu<>van<( nruter

D return (<nav><ul><li><a href="/home">Home</a></li><li><a href="/about">About</a></li><li><a href="/contact">Contact</a></li></ul></nav>);

💡 Hint

Check if all tags are properly closed.

Option B is missing a closing tag after the first element, causing a syntax error in JSX.

🔧 Debug

advanced

Why does this navigation component not update the active link?

This React component tries to highlight the active link but fails. What is the reason?

React

import React, { useState } from 'react';

export default function Nav() {
  let active = 'Home';

  return (
    <nav aria-label="Main navigation">
      <ul>
        <li>
          <button onClick={() => active = 'Home'} aria-current={active === 'Home' ? 'page' : undefined}>Home</button>
        </li>
        <li>
          <button onClick={() => active = 'About'} aria-current={active === 'About' ? 'page' : undefined}>About</button>
        </li>
        <li>
          <button onClick={() => active = 'Contact'} aria-current={active === 'Contact' ? 'page' : undefined}>Contact</button>
        </li>
      </ul>
    </nav>
  );
}

A The variable 'active' is not a state variable, so React does not re-render when it changes.

B The onClick handlers are missing parentheses, so they never run.

C The aria-current attribute is misspelled, so it does not update.

D The buttons should be anchor tags for navigation to work.

💡 Hint

React only re-renders when state or props change.

The variable 'active' is a plain variable. Changing it does not trigger React to re-render the component, so the UI does not update.

🧠 Conceptual

expert

Which option best describes the purpose of 'aria-current' in navigation links?

In accessible navigation components, what is the main role of the 'aria-current' attribute on links?

A It triggers a browser alert when the link is focused.

B It visually highlights the active link by changing its color automatically.

C It disables the link so users cannot click the current page link again.

D It informs assistive technologies which link represents the current page or section.

💡 Hint

Think about screen readers and accessibility.

'aria-current' is an accessibility attribute that tells screen readers which link is the current page, improving navigation clarity for users with disabilities.

Practice

1. What is the main purpose of using Link from react-router-dom in a React app?

easy

A. To create navigation links that change pages without reloading the browser

B. To style buttons with CSS

C. To fetch data from an API

D. To manage component state

Solution

1. Step 1: Understand the role of Link

   Link is used to navigate between pages in a React app without refreshing the whole page.

2. Step 2: Compare with other options

   Options A, C, and D describe unrelated tasks like styling, data fetching, and state management, which Link does not handle.

3. Final Answer:

   To create navigation links that change pages without reloading the browser -> Option A

4. Quick Check:

   Navigation without reload = B [OK]

Hint: Remember: <Link> changes pages without full reload [OK]

Common Mistakes:

• Confusing <Link> with HTML <a> tag behavior
• Thinking <Link> manages data or state
• Assuming <Link> reloads the page

2. Which of the following is the correct syntax to create a navigation link to '/about' using react-router-dom?

easy

A. About

B. About

C. About

D. About

Solution

1. Step 1: Identify correct attribute for Link

   The Link component uses the to attribute to specify the path.

2. Step 2: Differentiate from HTML anchor tag

   HTML a tags use href, but Link requires to. About uses correct syntax.

3. Final Answer:

   <Link to='/about'>About</Link> -> Option C

4. Quick Check:

   Link uses to attribute [OK]

Hint: Use 'to' with <Link>, 'href' with <a> [OK]

Common Mistakes:

• Using href instead of to with <Link>
• Using to attribute on <a> tag
• Mixing <Link> and <a> syntax

3. Given this React code snippet, what will be rendered on the page?

import { Link } from 'react-router-dom';

function Nav() {
  return (
    <nav>
      <Link to='/'>Home</Link>
      <Link to='/profile'>Profile</Link>
    </nav>
  );
}

medium

A. An error because <Link> cannot be used inside <nav>

B. Two clickable links labeled 'Home' and 'Profile' that navigate without page reload

C. Buttons that submit a form

D. Plain text 'Home' and 'Profile' with no navigation

Solution

1. Step 1: Analyze the JSX structure

   The component returns a <nav> element containing two <Link> components with paths '/' and '/profile'.

2. Step 2: Understand Link behavior

   Link renders as clickable links that navigate client-side without reloading the page.

3. Final Answer:

   Two clickable links labeled 'Home' and 'Profile' that navigate without page reload -> Option B

4. Quick Check:

   Links inside nav render clickable navigation [OK]

Hint: Links inside nav create clickable navigation [OK]

Common Mistakes:

• Thinking <Link> renders plain text
• Assuming <Link> causes page reload
• Believing <Link> cannot be inside <nav>

4. What is wrong with this React navigation code?

import { Link } from 'react-router-dom';

function Menu() {
  return (
    <nav>
      <Link href='/dashboard'>Dashboard</Link>
    </nav>
  );
}

medium

A. No import statement for React

B. Missing closing tag for <nav>

C. Link component cannot be used inside <nav>

D. Using 'href' instead of 'to' on <Link> causes navigation failure

Solution

1. Step 1: Check attribute usage on Link

   The Link component requires the to attribute, not href.

2. Step 2: Verify other code parts

   The <nav> tag is properly closed, and Link can be inside nav. React import is not mandatory in React 17+ for JSX.

3. Final Answer:

   Using 'href' instead of 'to' on <Link> causes navigation failure -> Option D

4. Quick Check:

   Link needs 'to', not 'href' [OK]

Hint: Use 'to' with <Link>, not 'href' [OK]

Common Mistakes:

• Using href attribute on <Link>
• Thinking <Link> can't be inside <nav>
• Assuming React import is always required

5. You want to create a navigation menu with links that have accessible names and keyboard focus. Which approach is best in React using react-router-dom?

hard

A. Use <nav> with <Link> components, add aria-label on nav, and ensure links have descriptive text

B. Use <div> with <Link> components and no ARIA labels

C. Use <nav> with <a> tags and href attributes for navigation

D. Use buttons with onClick handlers instead of links for navigation

Solution

1. Step 1: Choose semantic HTML for navigation

   The <nav> element is the correct semantic container for navigation links, improving accessibility.

2. Step 2: Use Link with descriptive text and ARIA labels

   Link components from react-router-dom provide client-side navigation. Adding aria-label on nav helps screen readers understand the menu purpose.

3. Step 3: Avoid incorrect elements

   Using div or buttons for navigation is less semantic and harms accessibility. Using a tags with href reloads pages, not client-side navigation.

4. Final Answer:

   Use <nav> with <Link> components, add aria-label on nav, and ensure links have descriptive text -> Option A

5. Quick Check:

   Semantic nav + Link + ARIA = A [OK]

Hint: Use semantic nav + Link + aria-label for accessible navigation [OK]

Common Mistakes:

• Using div instead of nav for navigation
• Skipping aria-label for screen readers
• Using buttons instead of links for navigation