Rule proposal: prefer-instanceof-element

[kidonng]

Checking the type of an element via element.tagName === 'name' doesn't give you type guard and you have to use optional chain (or ! a.k.a. Typescript's non-null assertion operator) if the element can be undefined or null.

Some elements have a corresponding JavaScript interface (e.g. HTMLImageElement for <img>), one can also use instanceof to check the element type without the aforementioned shortcomings.

An real life example is: 574d442 (#5036)

Fail

if (event.target.parentElement?.tagName === 'img') {
	return (target as HTMLImageElement).src
}

Pass

if (event.target.parentElement instanceof HTMLImageElement) {
	return target.src
}

[sindresorhus]

I think the rule scope and name should be more narrow. instanceof is generally not the best solution for most type-checks.

This will also most likely get solved in TypeScript at some point: microsoft/TypeScript#38839

[kidonng]

I think the rule scope and name should be more narrow. instanceof is generally not the best solution for most type-checks.

How about prefer-instanceof-element?

This will also most likely get solved in TypeScript at some point: microsoft/TypeScript#38839

I'm aware of that but it will probably take forever. And there are benefits outside TS too.

[sindresorhus]

I would name it prefer-instanceof-dom-element since element is a general term, for example, an element in a collection.

[sindresorhus]

I'm aware of that but it will probably take forever. And there are benefits outside TS too.

What are the non-TS benefits?