crafting (and) JavaScript

Cohesion and Coupling explained

Wikipedia says about cohesion, it refers to the degree to which the elements of a module belong together.
And about coupling it says how closely connected two routines or modules are.

See below for a very good short 6min video explaining how and why you should aim for high cohesion and loose coupling!
And if you want to spend more time watch this video 57min with all the stars :) discussing this topic more in detail.