CommonJS
CommonJS is a module specification for JavaScript that defines a standard for organizing and loading code modules, primarily used in server-side environments like Node.js. It introduces the `require()` function to import modules and `module.exports` or `exports` to export functionality, enabling modular programming in JavaScript. This system allows developers to break code into reusable pieces, manage dependencies, and avoid global namespace pollution.
Developers should learn CommonJS when working with Node.js or older JavaScript projects, as it was the default module system in Node.js for many years and is still widely used in legacy codebases. It's essential for understanding how to structure and share code in environments that don't natively support ES modules, such as in build tools or server applications where modularity is key for maintainability and scalability.