How Next.js renders (server-first model) - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to export a server component in Next.js.

NextJS

export default function [1]() { return <h1>Hello from server!</h1> }

Drag options to blanks, or click blank then click option'

APage

BServerComponent

CApp

DClientComponent

Attempts:

3 left

💡 Hint

Common Mistakes

Using ClientComponent name causes confusion with client components.

In Next.js, the default export named Page is recognized as a server component by default.

2fill in blank

medium

Complete the code to fetch data on the server side in a Next.js server component.

NextJS

export default async function Page() { const data = await fetch([1]); return <div>{JSON.stringify(data)}</div> }

Drag options to blanks, or click blank then click option'

A'/client/data'

B'/api/data'

C'/static/data'

D'/public/data'

Attempts:

3 left

💡 Hint

Common Mistakes

Fetching from /client/data is not a standard API route.

Server components can fetch data from API routes or external endpoints using fetch.

3fill in blank

hard

Fix the error in the code to mark a component as a client component in Next.js.

NextJS

"use client";

export default function [1]() { return <button>Click me</button> }

Drag options to blanks, or click blank then click option'

APage

BApp

CServerComponent

DClientComponent

Attempts:

3 left

💡 Hint

Common Mistakes

Using Page without client directive causes server rendering.

Client components must be marked with "use client" and can have any name, but ClientComponent is a clear name here.

4fill in blank

hard

Fill both blanks to create a server component that renders a list from fetched data.

NextJS

export default async function Page() {
  const data = await fetch([1]);
  const items = await data.json();
  return <ul>{items.map(item => <li key={item.id}>[2]</li>)}</ul>;
}

Drag options to blanks, or click blank then click option'

A'/api/items'

Bitem.name

Citem.title

D'/api/data'

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong API path or rendering wrong item property.

The server component fetches from /api/items and renders each item's name.

5fill in blank

hard

Fill all three blanks to create a client component with state and event handler in Next.js.

NextJS

"use client";

import { useState } from 'react';

export default function Counter() {
  const [count, setCount] = useState([1]);
  function handleClick() {
    setCount(count [2] 1);
  }
  return <button onClick=[3]>Count: {count}</button>;
}

Drag options to blanks, or click blank then click option'

A0

B+

ChandleClick

D1

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong initial state or wrong event handler name.

The client component initializes state to 0, increments count by 1 on click, and uses handleClick as event handler.

Practice

1. What is the main reason Next.js renders pages on the server first?

easy

A. To avoid using React components

B. To run JavaScript only on the client

C. To improve page load speed and SEO

D. To prevent any HTML from being sent to the browser

Solution

1. Step 1: Understand server-first rendering purpose

   Next.js renders pages on the server to send fully formed HTML to the browser quickly.

2. Step 2: Connect server rendering to SEO and speed

   Sending ready HTML helps search engines read content and users see pages faster.

3. Final Answer:

   To improve page load speed and SEO -> Option C

4. Quick Check:

   Server-first rendering = better speed and SEO [OK]

Hint: Server rendering means faster pages and better SEO [OK]

Common Mistakes:

• Thinking server rendering delays page load
• Believing React is not used in Next.js
• Assuming HTML is not sent to the browser

2. Which Next.js function is used to fetch data on the server before rendering a page?

easy

A. getServerSideProps

B. componentDidMount

C. useEffect

D. getStaticProps

Solution

1. Step 1: Identify server-side data fetching functions

   Next.js provides getServerSideProps to fetch data on the server at request time.

2. Step 2: Differentiate from other functions

   getStaticProps runs at build time, useEffect and componentDidMount run on client side.

3. Final Answer:

   getServerSideProps -> Option A

4. Quick Check:

   Server data fetch = getServerSideProps [OK]

Hint: Server data fetch uses getServerSideProps [OK]

Common Mistakes:

• Confusing getStaticProps with server-side fetching
• Using client hooks like useEffect for server data
• Thinking componentDidMount runs on server

3. Given this Next.js page code, what will the browser initially receive?

export async function getServerSideProps() {
  return { props: { message: 'Hello from server' } };
}

export default function Page({ message }) {
  return <h1>{message}</h1>;
}

medium

A. HTML with <h1>Hello from server</h1>

B. An empty page with no content

C. JavaScript code only, no HTML

D. A JSON object with the message

Solution

1. Step 1: Understand getServerSideProps role

   This function runs on the server and passes props to the component before rendering.

2. Step 2: Determine what is sent to browser

   The browser receives fully rendered HTML with the message inside an <h1> tag.

3. Final Answer:

   HTML with <h1>Hello from server</h1> -> Option A

4. Quick Check:

   Server props produce HTML output [OK]

Hint: Server props render HTML sent to browser first [OK]

Common Mistakes:

• Expecting raw JavaScript or JSON instead of HTML
• Thinking page is empty initially
• Confusing client-side rendering with server rendering

4. What is wrong with this Next.js page code?

export async function getServerSideProps() {
  const data = await fetch('https://api.example.com/data');
  return { props: { data } };
}

export default function Page({ data }) {
  return <div>{data.title}</div>;
}

medium

A. React components cannot use props

B. getServerSideProps cannot be async

C. Props cannot be passed to components

D. fetch returns a Response object, not JSON data

Solution

1. Step 1: Check fetch usage in getServerSideProps

   fetch returns a Response object; to get JSON, .json() must be called.

2. Step 2: Identify missing JSON parsing

   Without calling await data.json(), data is not the actual JSON, causing errors in rendering.

3. Final Answer:

   fetch returns a Response object, not JSON data -> Option D

4. Quick Check:

   fetch needs .json() to get data [OK]

Hint: Always parse fetch response with .json() in server props [OK]

Common Mistakes:

• Assuming fetch returns JSON directly
• Thinking getServerSideProps can't be async
• Believing props can't be passed to components

5. You want to render a page that shows a list of users fetched from an API on every request. Which Next.js approach correctly ensures the page is server-rendered with fresh data each time?

hard

A. Use getStaticProps to fetch users at build time

B. Use getServerSideProps to fetch users on each request

C. Fetch users inside useEffect in the component

D. Hardcode the user list in the component

Solution

1. Step 1: Understand data freshness needs

   Fetching fresh data on every request requires server-side fetching at request time.

2. Step 2: Match Next.js data fetching methods

   getServerSideProps runs on each request, while getStaticProps runs once at build time.

3. Step 3: Evaluate client-side fetching

   Fetching inside useEffect delays data until after page load, hurting SEO and initial render.

4. Final Answer:

   Use getServerSideProps to fetch users on each request -> Option B

5. Quick Check:

   Fresh server data = getServerSideProps [OK]

Hint: Fresh data each request? Use getServerSideProps [OK]

Common Mistakes:

• Using getStaticProps for dynamic data
• Fetching data only on client side
• Hardcoding data instead of fetching