JavaScript Modules Explained

Modules organize code into reusable pieces. Here's how they work in JavaScript.

Best Practices#

Organization:
✓ One export per file for large exports
✓ Use barrel files (index.js) for folders
✓ Keep related code together
✓ Avoid deep nesting

Naming:
✓ Use descriptive file names
✓ Match export name to file name
✓ Use camelCase for functions
✓ Use PascalCase for classes/components

Imports:
✓ Group imports logically
✓ External packages first
✓ Then internal modules
✓ Use absolute imports for clarity

Avoid:
✗ Circular dependencies
✗ Side effects in modules
✗ Mixing ESM and CommonJS
✗ Default exports for utilities

JavaScript modules enable clean code organization and reusability. Use ES modules for modern projects, understand CommonJS for Node.js compatibility, and leverage dynamic imports for code splitting. Keep modules focused, avoid circular dependencies, and structure imports for tree shaking.

JavaScript Modules Explained

ES Modules (ESM)#

Default Exports#

Re-exporting#

CommonJS (Node.js)#

Dynamic Imports#

Import Meta#

Module Patterns#

Circular Dependencies#

Browser vs Node.js#

TypeScript Modules#

Module Resolution#

Tree Shaking#

Best Practices#

Conclusion#

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