Why Barrel Files Are Hurting Your Codebase

August, 7th 2025 3 min read

Barrel files (index.ts or index.js) are often introduced in JavaScript and TypeScript projects to simplify imports. Instead of writing:

      import { Button } from '@/components/ui/Button';
import { Modal } from '@/components/ui/Modal';

You can write:

      import { Button, Modal } from '@/components/ui';

It’s shorter, cleaner — and a trap.

While barrel files may appear to reduce friction in small projects, they become a serious liability in large codebases. From performance degradation to broken types and circular dependencies, the problems outweigh the benefits.

🚨 What Is a Barrel File?

A barrel file is an index.ts or index.js file used to re-export modules from a directory:

1234

      // components/ui/index.ts
export * from './Button';
export * from './Modal';
export * from './Dropdown';

This allows you to import everything from a central location.

🔍 Why Barrel Files Are Problematic

1. They Obscure Dependency Graphs

Barrels flatten your module structure, making it harder to understand what depends on what. This hides circular dependencies that can cause runtime bugs or infinite loops in module resolution.

2. They Break Tree-Shaking

Barrels often force all exports to be bundled — even if you only import one module. This kills tree-shaking and increases bundle size, especially when using export *.

3. They Hurt Performance in Monorepos

In tools like Vite, Turbopack, and Rspack, barrels make it hard for the bundler to optimize file watching and cache invalidation. Touching one file in the barrel can trigger a full rebuild or reload.

4. They Break Type Safety in TypeScript

TypeScript may lose track of source locations when everything is re-exported. IntelliSense, go-to-definition, and refactors often fail silently.

5. They Obfuscate Refactors

Refactoring a single component becomes risky. Changing its name or location may require updating several barrels, or worse — you might miss one and end up with silent runtime bugs.

✅ What You Should Do Instead

1. Use Explicit Imports

Always import directly from the module you need:

      import { Button } from '@/components/ui/Button';

It may be longer, but it’s clearer and easier to debug.

2. Use Aliases Instead of Barrels

Use TypeScript’s paths or bundler aliasing to simplify imports without flattening:

json

1234

      // tsconfig.json
"paths": {
  "@ui/*": ["src/components/ui/*"]
}

      // usage
import { Button } from '@ui/Button';

3. Split Types and Components

Avoid re-exporting types and components together. If you must use a barrel, limit it to types only or define a strict public API.

4. Use Code Generators for Large Projects

Tools like Nx, Plop, or Hygen can automate import scaffolding without needing barrels.

💡 When Are Barrels Okay?

For types-only exports that won’t be bundled
For public APIs of libraries (not apps)
In design systems where component exposure is intentional

Still, even in those cases, you should prefer named exports and strict boundaries over export *.

🚫 A Real-World Example of Breakage

Consider this file structure:

plaintext

12345

      components/
  ui/
    Button.tsx
    Modal.tsx
    index.ts

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      // index.ts
export * from './Button';
export * from './Modal';

Now, if Modal.tsx imports Button, and another file imports both from ui, you’ve created a hidden circular dependency. You won’t notice until something randomly breaks in production.

🧼 Clean Imports > Clever Imports

Barrel files are clever — until they’re not. If you value type safety, refactor confidence, and performance, it’s time to rethink your import strategy.

Stop flattening your architecture. Embrace clear, explicit, and maintainable imports.