Server component execution model in NextJS - Mini Project: Build & Apply

Understanding Server Component Execution Model in Next.js

📖 Scenario: You are building a simple Next.js app that shows a greeting message fetched from a server component. This will help you understand how server components run on the server and send HTML to the browser.

🎯 Goal: Create a Next.js server component that returns a greeting message. Then add a configuration variable for the greeting text. Next, use the greeting text inside the server component. Finally, export the component as default to complete the setup.

📋 What You'll Learn

Create a server component function named Greeting

Add a constant variable greetingText with the value 'Hello from Server Component!'

Use the greetingText inside the Greeting component to display the message inside an <h1> tag

Export the Greeting component as the default export

💡 Why This Matters

🌍 Real World

Server components in Next.js help build fast web pages by running code on the server and sending ready HTML to the browser. This reduces JavaScript sent to users and improves performance.

💼 Career

Understanding server components is important for modern React and Next.js development jobs, as many companies use server components to optimize their web apps.

1

Create the Server Component Function

Create a server component function called Greeting that returns an <h1> tag with the text 'Welcome!'.

NextJS

// Create a server component function called Greeting
// Your code here

Hint

Remember, a server component is a function that returns JSX. Use function Greeting() and return an <h1> tag.

2

Add a Greeting Text Variable

Add a constant variable called greetingText with the value 'Hello from Server Component!' above the Greeting function.

NextJS

const greetingText = '';

export default function Greeting() {
  return Welcome!;
}

// Add a constant greetingText variable above the Greeting function

Hint

Use const greetingText = 'Hello from Server Component!'; before the function.

3

Use the Greeting Text in the Component

Change the Greeting function to return an <h1> tag that displays the greetingText variable instead of the fixed text.

NextJS

const greetingText = 'Hello from Server Component!';

export default function Greeting() {
  // Use greetingText inside the h1 tag
  return ;
}

// Replace the fixed text with greetingText variable

Hint

Use curly braces {} inside JSX to insert the variable greetingText.

4

Export the Component as Default

Ensure the Greeting function is exported as the default export using export default Greeting; at the end of the file.

NextJS

const greetingText = 'Hello from Server Component!';

function Greeting() {
  return {greetingText};
}

// Export Greeting as default export below

Hint

Use export default Greeting; to export the component.

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