chore: Address TiCS coding standards warnings for base JS

[steverydz]

Done

Addressed TiCS coding standards warnings for base JS

• Converted the parameters to an object for the triggerEvent function to meet the parameter limit requirement, which makes it clearer what each argument is for when using the function
• Added missing return types to functions
• Marked DOM selector elements as possibly undefined and added appropriate checks for their existence
• Renamed origin to urlLocation as origin is an existing global object
• Removed some unnecessary if conditions
• Fixed some basic linting errors

How to QA

All JS tests and linter checks should pass

Testing

• This PR has tests
• No testing required (explain why): No behavioural changes

[webteam-app]

Demo

Jenkins

demos.haus

[codeEmpress1]

LGTM!

[bartaz]

I'm not exactly sure if I understand the ! usage here.
We are telling TS, that this is not null (if I understand it correctly), but next line we actually have a conditional statement to check if it's not null (because then we look for a button instead).

[steverydz]

@bartaz Actually that makes sense - I meant to revert that change as I did on others on closer review. TiCS wants us to mark every selector as not null it seems, even though we can't always be sure about that. I'll fix that in the next PR.

[bartaz]

LGTM, with a question (in inline comment).