Event type for readystatechange is not specific enough

[jurosh]

TypeScript Version: 4.1.0 (probably all)

Search Terms: readystatechange, ProgressEvent

Code

document.addEventListener('readystatechange', event => {
  if (event.target?.readyState === 'complete') {
    // ready state
  }
});

Expected behavior:
For readystatechange event, when calling from document.addEventListener there is only single event target allowed and that is Document itself.
Spec:

• https://html.spec.whatwg.org/multipage/indices.html#event-readystatechange
• https://developer.mozilla.org/en-US/docs/Web/API/Document/readystatechange_event

So code above should be executable without typescript errors.

Actual behavior:
Currently there is no information about event.target. It's pointing to generic event interface.

Playground Link

[jurosh]

I've tried to make PR which would fix this #41776

• but problem is that file I edited is generated (and bot closed it) 😞
  I am not sure right now what is source of those typings, can take closer look later, or if someone can give me hand I can update accordingly

[jurosh]

Seems it would be required to modify https://github.com/microsoft/TypeScript-DOM-lib-generator/ and I have no idea how.
Please feel free to close issue if that is too much effort for just small typing security benefit.

[RyanCavanaugh]

That's the right repro for the fix, but we track the issues here sometimes too

[jonhue]

@RyanCavanaugh I suggest closing this here as @orta made a valid case against making the type more specific here (microsoft/TypeScript-DOM-lib-generator#969 (comment)).

[RyanCavanaugh]

Agreed