Rationale for KM JavaScript-in-browser style: enclose in (function () { ... } )();

[ComplexPoint]

See the step by step account of the various parts of an IIFE in this post:

Comparing JavaScript for Automation (JXA) and AppleScript

That's right – JavaScript interpreter environments, like Script Editor, and the JavaScript console in browsers, generally have a persistent global name space, containing a whole lot of definitions. It's a crowded space. You can see its contents by running the following one-word JS script in Script Editor: this (You will see a lot of crowded detail appearing in the Script Editor Results panel) If you don't write your code definitions inside a function wrapping, they are just added to this alr…