If you're just starting with Node.js, you might have come across two different ways to import and export code: CommonJS and ES Modules. They might seem a bit confusing at first, but once you understand the basics, it’s really not that hard.
What Are Modules, Anyway?
Before diving into the differences, let’s quickly talk about what a module is. Imagine you’re building a house. You wouldn’t want to carry all the bricks, windows, and doors in one go. Instead, you break them down into smaller parts and assemble them step by step. Similarly, in coding, a module is like a small, self-contained piece of your application. You can build your application step by step by combining different modules.
Difference between CommonJS and ES Modules
| Feature | CommonJS | ES Modules |
| Syntax | require for imports and module.exports for exports. | import for imports and export for exports. |
| File Extension | .js (default in Node.js) | .mjs or .js with "type": "module" in package.json. |
| Loading | Synchronous (modules are loaded one at a time). | Asynchronous (modules can be loaded simultaneously). |
| Flexibility | Less flexible, mainly used in Node.js. | More flexible, works in both Node.js and browsers. |
| Default Usage in Node.js | Default module system in Node.js. | Requires additional setup (like .mjs extension or "type": "module" in package.json). |
| Partial Import | Not natively supported; you usually import the whole module. | Supported; you can import only the parts you need. |
| Standardization | Specific to Node.js. | Standardized across JavaScript environments, including browsers. |
| Mode | Non-strict mode | Strict mode |
Which One Should You Use?
For most modern projects, ES Modules are the way to go because they are the standard and offer more flexibility. However, if you’re working with older Node.js projects or libraries that use CommonJS, you might need to stick with that for compatibility reasons.
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