Route prefetching behavior in NextJS

Introduction

Route prefetching helps your app load pages faster by getting them ready before you click. It makes navigation smooth and quick.

When you want to speed up page loading for links users are likely to click next.

When you want to improve user experience by reducing waiting time between pages.

When you have a multi-page app and want to prepare pages in the background.

When you want to optimize performance on slow networks by preloading important routes.

Syntax

NextJS

import Link from 'next/link';

<Link href="/about" prefetch={true}>About</Link>

The prefetch prop on Link controls if Next.js preloads the page.

By default, Next.js prefetches pages in the viewport when using next/link.

Examples

This disables prefetching for the Contact page link.

NextJS

<Link href="/contact" prefetch={false}>Contact</Link>

Default behavior: Next.js prefetches the Blog page when the link is visible.

NextJS

<Link href="/blog">Blog</Link>

Manually prefetch the Dashboard page on component load using the router.

NextJS

import { useEffect } from 'react';
import { useRouter } from 'next/router';

const Component = () => {
  const router = useRouter();

  useEffect(() => {
    router.prefetch('/dashboard');
  }, [router]);

  return <div>Dashboard Prefetch Example</div>;
};

Sample Program

This component shows three links with different prefetch behaviors. The About page is prefetched manually on load, Contact disables prefetch, and Blog uses default prefetching.

NextJS

import Link from 'next/link';
import { useRouter } from 'next/router';
import { useEffect } from 'react';

export default function Home() {
  const router = useRouter();

  useEffect(() => {
    // Manually prefetch the /about page
    router.prefetch('/about');
  }, [router]);

  return (
    <main>
      <h1>Welcome to Home</h1>
      <nav>
        <ul>
          <li><Link href="/about">About (prefetched manually)</Link></li>
          <li><Link href="/contact" prefetch={false}>Contact (no prefetch)</Link></li>
          <li><Link href="/blog">Blog (default prefetch)</Link></li>
        </ul>
      </nav>
    </main>
  );
}

Important Notes

Prefetching only works in production builds, not in development mode.

Prefetching uses idle browser time to avoid slowing down the main work.

Too much prefetching can waste bandwidth, so use it wisely.

Summary

Route prefetching loads pages in the background to speed up navigation.

You can control prefetching with the prefetch prop on Link or manually with router.prefetch().

Use prefetching to improve user experience but avoid overusing it to save bandwidth.

Practice

1. What is the main purpose of route prefetching in Next.js?

easy

A. To prevent users from navigating to certain pages

B. To disable client-side navigation

C. To load pages in the background before the user navigates to them

D. To increase the size of the initial JavaScript bundle

Solution

1. Step 1: Understand what prefetching means

   Prefetching means loading resources ahead of time before they are needed.

2. Step 2: Apply this to Next.js routing

   Next.js prefetches pages in the background to make navigation faster when the user clicks a link.

3. Final Answer:

   To load pages in the background before the user navigates to them -> Option C

4. Quick Check:

   Prefetching = background loading [OK]

Hint: Prefetching means loading before navigation happens [OK]

Common Mistakes:

• Thinking prefetching blocks navigation
• Confusing prefetching with disabling navigation
• Assuming prefetching increases initial load size

2. Which of the following is the correct way to disable automatic prefetching on a Next.js Link component?

easy

A. <Link href='/about' prefetch={false}>About</Link>

B. <Link href='/about' prefetch>About</Link>

C. <Link href='/about' noPrefetch>About</Link>

D. <Link href='/about' prefetch='off'>About</Link>

Solution

1. Step 1: Recall the prefetch prop usage

   The prefetch prop accepts a boolean to enable or disable prefetching.

2. Step 2: Identify the correct syntax to disable prefetching

   Setting prefetch={false} disables automatic prefetching on the Link.

3. Final Answer:

   <Link href='/about' prefetch={false}>About</Link> -> Option A

4. Quick Check:

   Disable prefetch with prefetch={false} [OK]

Hint: Use prefetch={false} to turn off prefetching [OK]

Common Mistakes:

• Using just 'prefetch' without value disables prefetching
• Using non-existent props like noPrefetch
• Passing string values instead of boolean

3. Consider this Next.js code snippet:

import Link from 'next/link';

export default function Home() {
  return (
    <div>
      <Link href='/profile' prefetch>Go to Profile</Link>
    </div>
  );
}

What happens when this component renders in the browser?

medium

A. The '/profile' page is not prefetched because prefetch defaults to false

B. The '/profile' page is prefetched in the background to speed up navigation

C. The link will cause a full page reload when clicked

D. The component will throw a syntax error due to incorrect prefetch usage

Solution

1. Step 1: Check the prefetch prop usage

   The prefetch prop is present without a value, which means it is true.

2. Step 2: Understand Next.js default behavior

   Next.js prefetches linked pages by default, so explicitly adding prefetch confirms this behavior.

3. Final Answer:

   The '/profile' page is prefetched in the background to speed up navigation -> Option B

4. Quick Check:

   prefetch present = prefetch enabled [OK]

Hint: Presence of prefetch prop means prefetching is on [OK]

Common Mistakes:

• Thinking prefetch defaults to false
• Assuming link causes full page reload
• Confusing syntax with errors

4. You wrote this code to prefetch a route manually:

import { useRouter } from 'next/router';
import { useEffect } from 'react';

export default function Page() {
  const router = useRouter();

  useEffect(() => {
    router.prefetch('/dashboard');
  }, []);

  return <div>Welcome</div>;
}

However, the prefetch does not seem to work. What is the likely cause?

medium

A. You must call router.prefetch inside an event handler, not useEffect

B. The router.prefetch method does not exist in Next.js

C. The router.prefetch method is asynchronous and needs to be awaited

D. The useRouter import path is incorrect; it should be from 'next/navigation'

Solution

1. Step 1: Check the import source of useRouter

   In Next.js 14+, useRouter for client navigation is imported from 'next/navigation', not 'next/router'.

2. Step 2: Understand impact on router.prefetch

   Importing from 'next/router' gives an outdated router without prefetch support, so prefetch won't work.

3. Final Answer:

   The useRouter import path is incorrect; it should be from 'next/navigation' -> Option D

4. Quick Check:

   Correct import = 'next/navigation' [OK]

Hint: Use 'next/navigation' for router.prefetch in Next.js 14+ [OK]

Common Mistakes:

• Importing useRouter from 'next/router' instead of 'next/navigation'
• Not awaiting async prefetch (not required)
• Thinking prefetch only works in event handlers

5. You want to optimize bandwidth by prefetching only when a user hovers over a link. Which approach correctly implements this in Next.js?

hard

A. Set prefetch={false} on Link and call router.prefetch() inside an onMouseEnter event handler

B. Set prefetch on Link and call router.prefetch() inside useEffect

C. Remove prefetch from Link and rely on default prefetching

D. Use prefetch={true} on Link and disable prefetching globally in config

Solution

1. Step 1: Disable automatic prefetching on the Link

   Set prefetch={false} to prevent Next.js from prefetching immediately.

2. Step 2: Prefetch manually on user hover

   Use onMouseEnter event to call router.prefetch() to load the page only when user shows interest.

3. Final Answer:

   Set prefetch={false} on Link and call router.prefetch() inside an onMouseEnter event handler -> Option A

4. Quick Check:

   Manual prefetch on hover = prefetch={false} + onMouseEnter [OK]

Hint: Disable auto prefetch, prefetch manually on hover event [OK]

Common Mistakes:

• Prefetching both automatically and manually causing wasted bandwidth
• Calling prefetch in useEffect instead of on hover
• Relying on default prefetching without control