Next.js Course
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Bundle Analysis

Definition

The process of visually inspecting the compiled JavaScript files produced by Next.js to identify massive dependencies that are slowing down the application.

Explain Like I'm New

Your site feels slow. You run a 'Bundle Analyzer'. It generates a visual map of your code that looks like a bunch of colored boxes. You notice a giant red box taking up 50% of the space. You realize you accidentally imported the entire `lodash` library instead of just one function. You fix the import, and your site gets 2x faster.

Real World Example

Discovering that importing `import { format } from 'date-fns'` pulls in all 150 languages supported by date-fns, ruining performance. You switch it to `import format from 'date-fns/format'`.

Common Use Cases

  • •Performance auditing
  • •Reducing bundle size

Interactive Example

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Interview Questions

basic

  • What popular plugin is used to visualize the Next.js JavaScript bundle?

intermediate

  • Why do Server Components make bundle analysis slightly less terrifying?

Flash Cards

Question

Which plugin?

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Answer

`@next/bundle-analyzer`

Question

Why less terrifying?

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Answer

Because dependencies imported into Server Components are NEVER sent to the browser bundle. You can import a massive 10 Megabyte library into a Server Component, and the user's bundle size stays perfectly at 0 bytes.