Use module, factory, strategy and composition patterns where they actually reduce complexity and duplication instead of making the codebase harder to read.
A good module groups one area of responsibility and exposes a small public surface.
Modules reduce accidental coupling because they let you organize behavior by concern instead of leaving everything in one global file.
The biggest win is not fashion. It is that reading and testing the code becomes easier when the public API is small.
A factory makes sense when creating an object requires more than copying literal fields.
Factories are helpful when new objects need defaults, computed values or environment-specific behavior at creation time.
They also make creation logic easier to evolve than duplicating ad hoc object literals everywhere.
When behavior changes by context, separate the variations instead of growing one giant `if` chain.
A strategy object or function map lets the code select behavior based on one key instead of embedding every variation into the same flow.
Composition then combines those pieces so you build capability from small functions instead of one enormous feature block.