IIFE in classlist_polyfills.js

[Aditya-Basak]

Sir, my question would be as to why we used IIFE in classlist_polyfills.js whereas it has not been used in the other polyfills classes? As in, what exactly is special about this polyfills that separates it from the other polyfills?
The second part of the question would be, how is it actually testing the existence of the functionality which is the first step in polyfills writing?
Although it might not exactly be an issue, I would be eagerly waiting for a clarification.

[sigod]

why we used IIFE in classlist_polyfills.js whereas it has not been used in the other polyfills classes?

Wikipedia explains it:
https://en.wikipedia.org/wiki/Immediately-invoked_function_expression#Examples

[Aditya-Basak]

Okay so going through what you suggested I guess other polyfills would be invoked as and when it's required according to the functionality and execution of the game. We don't want them to be executed pre-maturely. But classlist_polyfills.js interacts with the HTML and CSS required for the game's appearance which anyway needs to be loaded at the very beginning of the game every time the index.HTML page is opened in a browser. So making them an IIFE is justified.
Thanks for your response. It helped a lot in my understanding.
I hope I am not much mistaken, but if so, please correct me.

[sigod]

so going through what you suggested I guess other polyfills would be invoked as and when it's required according to the functionality and execution of the game. We don't want them to be executed pre-maturely.

No. Read here about polyfills: https://en.wikipedia.org/wiki/Polyfill

But classlist_polyfills.js interacts with the HTML and CSS required for the game's appearance which anyway needs to be loaded at the very beginning of the game every time the index.HTML page is opened in a browser. So making them an IIFE is justified.

Main use for IIFE is to declare a scope. classlist_polyfill has few functions and some variables that mustn't be exposed outside of it. If classlist_polyfill haven't used enclosing function defineElementGetter, DOMTokenList and other variables would've been exposed and possibly modified by other code. Which would lead to undefined behavior.