Why server components are the default in NextJS - Test Your Understanding

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create 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'

Adocument.getElementById('root')

BuseState()

CuseEffect()

D"Hello from server component!"

Attempts:

3 left

💡 Hint

Common Mistakes

Trying to use useState or useEffect in server components.

The server component returns JSX directly without client 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.json();
  return <div>[1]</div>;
}

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

Adata.message

BuseState(data)

Cconsole.log(data)

Ddocument.querySelector('div')

Attempts:

3 left

💡 Hint

Common Mistakes

Using client hooks or DOM methods in server components.

Server components can fetch data and render it directly in JSX.

3fill in blank

hard

Fix the error in this server component by completing the code.

NextJS

import { useState } from 'react';

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

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

AuseMemo(0)

BuseState(0)

Cfetch(0)

DuseEffect(0)

Attempts:

3 left

💡 Hint

Common Mistakes

Trying to use useState in server components.

useState is a client hook and cannot be used in server components. This code causes an error because server components do not support client hooks.

4fill in blank

hard

Fill both blanks to mark a component as client and use state.

NextJS

"use client";
import { [1] } from 'react';

export default function Clicker() {
  const [count, setCount] = [2](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

Forgetting "use client" directive.

Using hooks not related to state.

Adding "use client" marks the component as a client component. useState is imported and used to manage state.

5fill in blank

hard

Fill all three blanks to fetch data in a server component and render it safely.

NextJS

export default async function Profile() {
  const res = await fetch('/api/user');
  const user = await res.[1]();
  if (!user) return <p>No user found</p>;
  return <section>
    <h1>[2]</h1>
    <p>Email: [3]</p>
  </section>;
}

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

Ajson

Buser.name

Cuser.email

Dtext

Attempts:

3 left

💡 Hint

Common Mistakes

Using res.text() instead of res.json().

Trying to access properties before parsing.

Use res.json() to parse the response. Then render user.name and user.email safely in JSX.

Practice

1. Why are server components the default in Next.js?

easy

A. They allow direct access to browser events and state management.

B. They improve speed by running on the server and sending only HTML to the browser.

C. They require less server resources by running on the client.

D. They enable real-time updates without refreshing the page.

Solution

1. Step 1: Understand server component behavior

   Server components run on the server and send only HTML to the browser, reducing data transfer and improving speed.

2. Step 2: Compare with client components

   Client components handle browser events and state, but server components focus on fast, secure rendering.

3. Final Answer:

   They improve speed by running on the server and sending only HTML to the browser. -> Option B

4. Quick Check:

   Server components = faster, secure HTML delivery [OK]

Hint: Server components send HTML, client components handle events [OK]

Common Mistakes:

• Confusing server components with client-side event handling
• Thinking server components run in the browser
• Assuming server components manage state like client components

2. Which of the following is the correct way to mark a component as a client component in Next.js?

easy

A. Use export default clientComponent() syntax.

B. Wrap the component in <ClientComponent> tags.

C. Add the directive use client at the top of the file.

D. Add client: true in the component props.

Solution

1. Step 1: Recall client component syntax

   In Next.js, to mark a component as client-side, you add the directive use client at the very top of the file.

2. Step 2: Eliminate incorrect options

   Wrapping in tags, special export syntax, or props flags are not valid ways to mark client components.

3. Final Answer:

   Add the directive use client at the top of the file. -> Option C

4. Quick Check:

   Client component directive = 'use client' [OK]

Hint: Client components start with 'use client' directive [OK]

Common Mistakes:

• Trying to mark client components with props or wrappers
• Placing 'use client' inside the component body
• Confusing export syntax with client directives

3. Consider this Next.js component code:

export default function Page() {
  return (
    <div>Hello from server component</div>
  )
}

What will the browser receive when this page loads?

medium

A. Plain HTML content: <div>Hello from server component</div>.

B. An error because no client directive is present.

C. A fully interactive React component with event handlers.

D. Empty content because server components do not render.

Solution

1. Step 1: Identify component type

   The component has no 'use client' directive, so it is a server component by default.

2. Step 2: Understand server component output

   Server components render HTML on the server and send plain HTML to the browser without React event handlers.

3. Final Answer:

   Plain HTML content: <div>Hello from server component</div>. -> Option A

4. Quick Check:

   Server component output = plain HTML [OK]

Hint: No 'use client' means server component sends HTML only [OK]

Common Mistakes:

• Expecting React interactivity without 'use client'
• Thinking server components cause errors without client directive
• Assuming server components send JavaScript to browser

4. You have this Next.js component:

export default function Button() {
  const [count, setCount] = React.useState(0);
  return <button onClick={() => setCount(count + 1)}>Clicked {count} times</button>;
}

What is the main problem with this code in Next.js 13+?

medium

A. Buttons cannot have event handlers in Next.js.

B. The useState hook is not imported from React.

C. The arrow function in onClick is invalid syntax.

D. It lacks the use client directive, so state and events won't work.

Solution

1. Step 1: Check component type and hooks usage

   The component uses React state and event handlers, which require client-side execution.

2. Step 2: Identify missing client directive

   Without the 'use client' directive at the top, this component is treated as a server component, so hooks and events won't work.

3. Final Answer:

   It lacks the use client directive, so state and events won't work. -> Option D

4. Quick Check:

   State + events need 'use client' directive [OK]

Hint: State or events require 'use client' directive [OK]

Common Mistakes:

• Forgetting to add 'use client' for interactive components
• Assuming hooks work in server components
• Thinking arrow functions cause syntax errors here

5. You want to build a Next.js page that fetches data securely on the server and shows a button that increments a counter on click. How should you organize your components?

hard

A. Use a server component for data fetching and embed a client component for the button with state.

B. Make the entire page a client component to handle data fetching and button state.

C. Use only server components because client components are slower.

D. Fetch data in the client component and handle button state in the server component.

Solution

1. Step 1: Separate concerns by component type

   Data fetching is best done in server components for security and speed, while interactive UI needs client components.

2. Step 2: Combine server and client components properly

   Use a server component to fetch and render data, then include a client component inside it for the button with state and events.

3. Final Answer:

   Use a server component for data fetching and embed a client component for the button with state. -> Option A

4. Quick Check:

   Server fetch + client interactivity = best practice [OK]

Hint: Fetch on server, interactive parts on client [OK]

Common Mistakes:

• Making entire page client-side losing server benefits
• Trying to fetch data inside client components
• Mixing state logic in server components