UNDERSTANDING THE MODULE PATTERN

Splitting code into independent pieces and connecting those pieces together can be robustly implemented with the module pattern. The central ideas for this pattern are simple: break logic into pieces that are totally encapsulated from the rest of the code, allow each piece to explicitly define what parts of itself are exposed to external pieces, and allow each piece to explicitly define what external pieces it needs to execute. There are various implementations and features that complicate these concepts, but these fundamental ideas are the foundation for all module systems in JavaScript.

Module Identifiers

Common to all module systems is the concept of module identifiers. Module systems are essentially key-value entities, where each module has an identifier that can be used to reference it. This token will sometimes be a string in cases where the module system is emulated, or it might be an actual path to a module file in cases where the module system...