How Next.js renders (server-first model) - Try It Yourself

How Next.js renders (server-first model)

📖 Scenario: You are building a simple Next.js app that shows a welcome message fetched from the server. This will help you understand how Next.js renders pages first on the server before sending them to the browser.

🎯 Goal: Create a Next.js app with a server component that fetches a message and displays it. You will set up the data, configure a fetch function, use the server component to render the message, and complete the page structure.

📋 What You'll Learn

Create a server component that fetches data

Use async/await to fetch the message

Render the fetched message inside a React component

Use Next.js App Router conventions with a page.tsx file

💡 Why This Matters

🌍 Real World

Next.js is used to build fast websites that load content on the server first, improving performance and SEO.

💼 Career

Understanding server-first rendering in Next.js is essential for frontend developers working with modern React frameworks and building scalable web apps.

1

DATA SETUP: Create a simple message variable

Create a constant called message with the exact string value 'Welcome to Next.js server-first rendering!'.

NextJS

// Create a constant called message with the exact string value
// Your code here

Hint

Use const message = '...' to create the message string.

2

CONFIGURATION: Create an async function to fetch the message

Create an async function called fetchMessage that returns the message constant.

NextJS

const message = 'Welcome to Next.js server-first rendering!';

// Create an async function fetchMessage that returns message
// Your code here

Hint

Define async function fetchMessage() { return message; }.

3

CORE LOGIC: Create a server component that uses fetchMessage

Create an async React component called Welcome that calls fetchMessage(), awaits its result, and returns a <div> containing the message inside a <p> tag.

NextJS

const message = 'Welcome to Next.js server-first rendering!';

async function fetchMessage() {
  return message;
}

// Create an async React component Welcome that fetches the message and renders it
// Your code here

Hint

Use export default async function Welcome() { const msg = await fetchMessage(); return (<div><p>{msg}</p></div>); }.

4

COMPLETION: Add the page metadata export

Add an export called metadata with a title property set to 'Next.js Server Rendering'.

NextJS

const message = 'Welcome to Next.js server-first rendering!';

async function fetchMessage() {
  return message;
}

export default async function Welcome() {
  const msg = await fetchMessage();
  return (
    
      {msg}
    
  );
}

// Add export metadata with title 'Next.js Server Rendering'
// Your code here

Hint

Use export const metadata = { title: 'Next.js Server Rendering' };.

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