Why server components are the default in NextJS - See It in Action

Why Server Components Are the Default in Next.js

📖 Scenario: You are building a simple Next.js app that shows a greeting message and the current date and time. You want to understand why Next.js uses server components by default to improve performance and user experience.

🎯 Goal: Create a Next.js app with a server component that renders a greeting and the current date/time on the server, then add a client component that updates the time every second. This will show how server components handle static content by default and client components handle dynamic updates.

📋 What You'll Learn

Create a server component named Greeting that displays a greeting message and the current date/time.

Create a client component named Clock that updates the time every second.

Use the use client directive in the client component.

Render the Greeting component in the main page and include the Clock component inside it.

Ensure the server component fetches the date/time only once on the server.

Ensure the client component updates the time dynamically on the browser.

💡 Why This Matters

🌍 Real World

Many modern web apps use server components to improve performance by sending pre-rendered HTML and only loading JavaScript when needed for interactivity.

💼 Career

Understanding server and client components in Next.js is essential for building fast, scalable React apps and is a key skill for frontend and full-stack developers.

1

Create the Server Component

Create a server component named Greeting in a file called Greeting.jsx. It should return a div with a h1 that says "Hello from Server Component!" and a p that shows the current date and time using new Date().toLocaleString().

NextJS

// Your code here

Hint

Remember, server components run on the server and can use JavaScript directly to get the current date/time once.

2

Create the Client Component

Create a client component named Clock in a file called Clock.jsx. Add the directive 'use client' at the top. Use useState and useEffect to update the current time every second. Render the current time inside a p tag.

NextJS

export default function Greeting() {
  const currentTime = new Date().toLocaleString();
  return (
    
      Hello from Server Component!
      Current time: {currentTime}
      {/* Add Clock component here */}
    
  );
}

// Your code here

Hint

Use useState to hold the time and useEffect to update it every second with setInterval.

3

Render the Server Component in the Main Page

In the main page file page.jsx, import the Greeting server component and render it inside the default exported function.

NextJS

// Your code here

Hint

Import the Greeting component and render it inside the main page's default export.

4

Explain Why Server Components Are Default

Add a comment at the top of Greeting.jsx explaining that server components are the default in Next.js because they run on the server, reduce client bundle size, and improve performance by sending ready HTML to the browser.

NextJS

// Your comment here
import Greeting from './Greeting';

export default function Page() {
  return ;
}

export default function Greeting() {
  const currentTime = new Date().toLocaleString();
  return (
    
      Hello from Server Component!
      Current time: {currentTime}
      
    
  );
}

'use client';

import { useState, useEffect } from 'react';

export function Clock() {
  const [time, setTime] = useState(new Date().toLocaleString());

  useEffect(() => {
    const timer = setInterval(() => {
      setTime(new Date().toLocaleString());
    }, 1000);
    return () => clearInterval(timer);
  }, []);

  return Updated time: {time};
}

Hint

Write a clear comment explaining the benefits of server components as the default in Next.js.

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