Node.js is currently in a transitional period between two powerful module systems.
1CommonJS (The Veteran)
Since its inception, Node.js has relied on CommonJS. It's robust, synchronous, and allows you to load modules conditionally inside if statements. However, it's not natively compatible with browsers.
2ES Modules (The Standard)
ESM is the official standard for JavaScript. It supports top-level await, static analysis, and tree-shaking, which makes your bundles smaller and faster. It is now the recommended way to write new Node.js apps.
3Interoperability
While you can use both, mixing them can be tricky. You can import CJS modules into ESM, but using require() for ESM files is generally not supported without experimental flags.
