Add Javascript Types w/JSDoc

[joshistoast]

PR Summary:

Add JSDoc documentation to javascript functions and classes where applicable.

Why are these changes introduced?

JSDoc is the nest best thing to native JS types. Typing our functions means better understanding of the parameters required and what gets returned without needing to crawl the codebase.

What approach did you take?

Classes, and functions with parameters and returns get JSDoc comments.

Other considerations

Decision log

#	Decision	Alternatives	Rationale	Downsides
1

Visual impact on existing themes

No visual impact.

Testing steps/scenarios

• Step 1

Demo links

• Store
• Editor

Checklist

• Added PR summary for release notes
• Requested review from UX (Only for changes that are affecting the experience or perceivable visual details)
• Created a ticket for the help.shopify.com documentation team about updates to theme settings. (Internal-only task)
• Followed theme code principles
• Linted with Theme Check
• Tested on mobile
• Tested on multiple browsers
• Tested for accessibility

[joshistoast]

will be adding more over next week if I have time

[thagxt]

It would be very handy to have these in all JS files, not just Global.

[joshistoast]

It would be very handy to have these in all JS files, not just Global.

That's the plan

[joshistoast]

Learning so much about JSDoc, and how much I dislike certain approaches to JS things in this codebase

[joshistoast]

Unfortunate with how many conditional class definitions there are, references to the types are unresolved when definitions are nested in a conditional.

Might be a good way to prevent defining classes multiple times on a page without wrapping the whole thing in a conditional 🤔

[joshistoast]

Ready for review, but not ready for merge.