CommonJS Modules
CommonJS Modules is a module system specification primarily used in server-side JavaScript environments, such as Node.js, to organize code into reusable modules. It defines a synchronous, file-based approach where each module is a separate file, and dependencies are loaded using the `require()` function, with exports defined via `module.exports` or `exports`. This system enables modular programming, code encapsulation, and dependency management in JavaScript applications.
Developers should learn CommonJS Modules when working with Node.js or legacy JavaScript projects, as it is the default module system in Node.js for many years and widely used in server-side development. It is essential for building scalable applications by breaking code into manageable pieces, handling dependencies, and facilitating code reuse, particularly in environments where synchronous loading is acceptable, such as backend services or build tools.