[Suggestion] document.getElementById is not correctly typed in TypeScript

[Judekeyser]

In TypeScript, getElementById returns a HTMLElement, while the standard mandates it to return a Element in order to account for more general situations like SVGElement and alike.

This change seems to be refused by TypeScript, for many years now:

• document.getElementById is not correctly typed microsoft/TypeScript#60996 (comment)
• Node.parentElement should be Element | null, not HTMLElement | null microsoft/TypeScript-DOM-lib-generator#1151 (comment)
• Update lib dom for 4.2 microsoft/TypeScript#42067 (comment)
• Node.parentElement should be Element, not HTMLElement microsoft/TypeScript#4689 (comment)

[uhyo]

Thank you for suggestion. I think I'd accept a fix.

Even if we only consider ordinary HTML documents, they could include SVG elements that are not HTMLElements.