Build output analysis in NextJS - Mini Project: Build & Apply

Build Output Analysis in Next.js

📖 Scenario: You are working on a Next.js project. You want to understand how the build output looks and how to analyze it to improve your app's performance.

🎯 Goal: Learn how to generate and analyze the build output of a Next.js app using the next build command and inspect the generated files.

📋 What You'll Learn

Create a simple Next.js app with a basic page

Add a configuration variable to enable build output tracing

Run the build command and capture the output files

Analyze the build output files and add a summary comment

💡 Why This Matters

🌍 Real World

Understanding build output helps developers optimize Next.js apps for faster loading and smaller bundles.

💼 Career

Knowing how to analyze and configure build output is important for frontend engineers working with Next.js in production environments.

1

Create a basic Next.js page

Create a file called pages/index.js with a React functional component named HomePage that returns an <h1> element with the text "Welcome to Next.js Build Analysis".

NextJS

// Create the HomePage component in pages/index.js
// Your code here

Need a hint?

This is a simple React functional component that returns a heading.

2

Add build output tracing configuration

In the root of your project, create or update next.config.js to export an object with experimental: { outputFileTracing: true } to enable build output tracing.

NextJS

export default function HomePage() {
  return Welcome to Next.js Build Analysis;
}

// Create next.config.js with outputFileTracing enabled
// Your code here

Need a hint?

This setting helps Next.js track which files are used in the build output.

3

Run the build and inspect output files

Run next build in your terminal to generate the production build. Then, in your project folder, locate the .next/server/pages/index.js file and note that it contains the server-side code for your page.

NextJS

export default function HomePage() {
  return Welcome to Next.js Build Analysis;
}

// next.config.js
module.exports = {
  experimental: {
    outputFileTracing: true
  }
};

// Run `next build` in terminal and check .next/server/pages/index.js
// Your code here

Need a hint?

Use your terminal to run next build and then explore the .next/server/pages folder.

4

Add a summary comment about build output

Add a comment at the end of pages/index.js explaining that the build output files include server and client bundles, and that output tracing helps reduce bundle size by including only used files.

NextJS

export default function HomePage() {
  return Welcome to Next.js Build Analysis;
}

// Add a summary comment about build output here
// Your code here

Need a hint?

Write a clear comment summarizing what you learned about the build output.