Server component execution model in NextJS - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

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

NextJS

export default function Home() {
  return <main>[1]</main>;
}

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

AuseEffect(() => {})

BuseState('Hello')

C<ClientComponent />

D"Hello from server component!"

Attempts:

3 left

💡 Hint

Common Mistakes

Using client hooks like useState or useEffect inside server components.

Trying to render client components directly without wrapping.

The server component returns JSX directly as a function without hooks like useState or useEffect.

2fill in blank

medium

Complete the code to fetch data in a server component using async/await.

NextJS

export default async function Data() {
  const res = await fetch('/api/data');
  const data = await res.[1]();
  return <pre>{JSON.stringify(data)}</pre>;
}

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

Atext

Bblob

Cjson

DformData

Attempts:

3 left

💡 Hint

Common Mistakes

Using text() which returns raw string instead of parsed JSON.

Using client-only hooks to fetch data.

To parse JSON response, use res.json() in async server components.

3fill in blank

hard

Fix the error in the server component by completing the code to mark it as a client component.

NextJS

"use client";

import { useState } from 'react';

export default function Counter() {
  const [count, setCount] = [1](0);
  return <button onClick={() => setCount(count + 1)}>{count}</button>;
}

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

AuseState

BuseEffect

CuseMemo

DuseRef

Attempts:

3 left

💡 Hint

Common Mistakes

Trying to use useState in server components without marking them as client.

Using hooks that don't manage state for this purpose.

Client components can use useState to manage state, but server components cannot.

4fill in blank

hard

Fill both blanks to correctly fetch data and render it in a server component.

NextJS

export default async function User() {
  const response = await fetch('/api/user');
  const user = await response.[1]();
  return <h1>[2]</h1>;
}

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

Ajson

Btext

Cuser.name

Duser

Attempts:

3 left

💡 Hint

Common Mistakes

Using text() which returns a string, not an object.

Trying to render the whole user object directly instead of a property.

Use json() to parse the response, then access user.name to display the user's name.

5fill in blank

hard

Fill all three blanks to create a server component that fetches posts and renders their titles.

NextJS

export default async function Posts() {
  const res = await fetch('/api/posts');
  const posts = await res.[1]();
  return (
    <ul>
      {posts.[2](post => (
        <li key={post.id}>[3]</li>
      ))}
    </ul>
  );
}

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

Ajson

Bmap

Cpost.title

Dfilter

Attempts:

3 left

💡 Hint

Common Mistakes

Using filter instead of map for rendering.

Trying to render the whole post object instead of its title.

Parse JSON data, then use map to loop over posts and render each post's title.

Practice

1. What is the main purpose of a Next.js server component?

easy

A. To manage browser events like clicks and form submissions

B. To handle client-side user interactions and state updates

C. To run code only on the server and send pre-rendered HTML to the client

D. To load CSS styles dynamically on the client

Solution

1. Step 1: Understand server component role

   Server components run only on the server and generate HTML before sending it to the browser.

2. Step 2: Compare with client components

   Client components handle interactions and state, but server components focus on data fetching and static rendering.

3. Final Answer:

   To run code only on the server and send pre-rendered HTML to the client -> Option C

4. Quick Check:

   Server components = server-only rendering [OK]

Hint: Server components run on server, not browser [OK]

Common Mistakes:

• Confusing server components with client components
• Thinking server components handle user events
• Assuming server components run in the browser

2. Which of the following is the correct way to define a Next.js server component?

easy

A. export default async function MyComponent() { return Hello from server }

B. 'use client';\nexport const runtime = 'edge'; export default function MyComponent() { return Hello }

C. 'use client';\nexport const dynamic = 'force-dynamic'; export default function MyComponent() { return Hello }

D. 'use client';\nexport default function MyComponent() { return Hello } // runs on client

Solution

1. Step 1: Identify server component syntax

   Server components can be async functions that fetch data and return JSX.

2. Step 2: Check options for server component traits

   export default async function MyComponent() { return <div>Hello from server</div> } exports an async function returning JSX, which is valid for server components.

3. Final Answer:

   export default async function MyComponent() { return <div>Hello from server</div> } -> Option A

4. Quick Check:

   Async function export = server component [OK]

Hint: Async function export usually means server component [OK]

Common Mistakes:

• Assuming all exported functions run on client
• Confusing runtime or dynamic exports with server component definition
• Not using async when fetching data in server components

3. Given this Next.js server component code, what will be rendered in the browser?

export default async function Page() {
  const data = await fetch('https://api.example.com/data').then(res => res.json())
  return <div>Count: {data.count}</div>
}

medium

A. Client-side loading spinner until data arrives

B. An error because fetch is not allowed in server components

C. Empty div because data is undefined

D. <div>Count: 42</div> (assuming API returns { count: 42 })

Solution

1. Step 1: Understand server component data fetching

   Server components can fetch data using await and render the result directly.

2. Step 2: Predict output with given API response

   If API returns { count: 42 }, the component renders <div>Count: 42</div> as static HTML.

3. Final Answer:

   <div>Count: 42</div> (assuming API returns { count: 42 }) -> Option D

4. Quick Check:

   Server fetch + await = pre-rendered data [OK]

Hint: Server components fetch data before rendering [OK]

Common Mistakes:

• Thinking fetch is disallowed in server components
• Expecting client-side loading states in server components
• Assuming data is undefined without awaiting fetch

4. Identify the error in this Next.js server component code:

export default function Page() {
  const data = fetch('/api/data').then(res => res.json())
  return <div>Data: {data.value}</div>
}

medium

A. Missing async/await causes data to be a Promise, not resolved value

B. fetch cannot be used inside server components

C. JSX syntax error in return statement

D. Using relative URL in fetch is not allowed on server

Solution

1. Step 1: Check fetch usage in server component

   fetch returns a Promise; without await, data is a Promise object.

2. Step 2: Understand JSX rendering with Promise

   JSX cannot render a Promise directly, causing incorrect output or error.

3. Final Answer:

   Missing async/await causes data to be a Promise, not resolved value -> Option A

4. Quick Check:

   Always await fetch in server components [OK]

Hint: Always await fetch to get data, not Promise [OK]

Common Mistakes:

• Forgetting async keyword on function
• Trying to render Promise instead of data
• Assuming fetch is disallowed in server components

5. How can you combine server components with client components in Next.js to fetch data securely and handle user interactions?

hard

A. Fetch data inside client component and send it back to server component via props

B. Use a server component to fetch data and pass it as props to a client component for interaction

C. Use only client components for both data fetching and interactions

D. Use server components to handle user events and client components to fetch data

Solution

1. Step 1: Understand server and client component roles

   Server components fetch data securely and prepare HTML; client components handle user events.

2. Step 2: Combine by passing data as props

   Server component fetches data, then passes it to client component which manages interactions.

3. Final Answer:

   Use a server component to fetch data and pass it as props to a client component for interaction -> Option B

4. Quick Check:

   Server fetch + client interaction = Use a server component to fetch data and pass it as props to a client component for interaction [OK]

Hint: Server fetches data, client handles UI events [OK]

Common Mistakes:

• Fetching data in client component only
• Trying to handle user events in server components
• Passing data from client to server component via props