Thanks for the PR!

This section of the codebase is owned by @saschanaz - if they write a comment saying "LGTM" then it will be merged.

Probably better to autodetect whether there's inheritance/mixin relationship and use this automatically in such case, wdyt? (In that case anything related to HTMLElement should be excluded for now or otherwise all the HTML event handlers would get this.)

But in case this is urgent I think this is fine too.

I think that's theoretically a good idea. But .. how many inheritance/mixin relationships are there? Even though this: this is correct I'd prefer to default it off for performance reasons.

If we do this, would you recommend putting the HTMLElement exclusion in overridingtypes.jsonc or hard-coded in the generator?

Edit: looks like there are around 120 mixins.

However, when I add manual exclusions, there are only 3 of them: AbstractWorker, GlobalEventHandlers and WindowEventHandlers. I'll try to come up with a property for overridingTypes.jsonc.

Unfortunately, this solution still makes Worker invariant and breaks on examples like partytown's tests:

interface PartytownWorker {
  // ...
}
interface TestWorker extends PartytownWorker {
  messages: any[]
}
// but you can't use a TestWorker as a PartytownWorker
// because this: this is ultimately invariant
declar var tw: TestWorker
var ptw: PartytownWorker = tw

@rbuckton suggested making MessageEventTarget generic so that Worker and the other extenders can specify a fixed this type:

interface MessageEventTarget<T> {
  onmessage: ((this: T, ...
}
interface Worker extends MessageEventTarget<Worker> {
}

This is a delimited form of this: this that stops with Worker (and GlobalEventHandler and WindowEventHandler). I'll see if I can figure out how to emit this.

microsoft/TypeScript#60987 is the PR I'm using to test this on TS.