Node.js
Facts
CommonJS Modules
Wrapping
Modules in NodeJS are not actually executed as-is. Instead, they are wrapped in a function - this function comes with parameters, like:
- require - the
requirefunction - module - we se the module’s exports here
- others
The require function returns what module sets in module.exports - it can do
it, because require actually INVOKES the wrapper function, and provides to it
the fresh instance of Module.
Multiple requires
If we call require to import the same module multiple times (from the same
file or from other files, doesn’t matter), the module’s code will be executed
only once! If our module would export some object, modification of that object
would be seen EVERYWHERE where this module gets imported.
It makes it easy to have singleton modules.