Finding and loading CommonJS and JSON modules using require

We have talked about several types of modules: CommonJS, JSON, ES2015, and native code modules. All but the ES2015 modules are loaded using the require function. That function has a very powerful and flexible algorithm for locating modules within a directory hierarchy. This algorithm, coupled with the npm package management system, gives the Node.js platform a lot of power and flexibility.

File modules

The CommonJS and ES2015 modules we've just looked at are what the Node.js documentation describes as a file module. Such modules are contained within a single file, whose filename ends with .js, .mjs, .json, or .node. The latter are compiled from C or...