Change WidgetType.updateDOM from type to this

[not-my-profile]

With this TypeScript understands that it's the same type as the subclass.

[marijnh]

The this type means more than just "of the same class as this" in TypeScript, unfortunately. It asserts that the value is actually equal to this, and will cause weird type narrowing to happen. So unfortunately, though I agree it would be better to have a more precise type for this parameter, this isn't appropriate here.

[not-my-profile]

I'm not sure that's the case? Do you have an example for the "weird type narrowing" because I can't manage to reproduce it:

class Foo {
  prop: string = "";

  test(other: this) {
    if (this.prop == 'certain') {
      this.prop; // narrowed to 'certain'
      other.prop; // still string
    }
  }
}

TS Playground

[marijnh]

It seems you are right. I distinctly remember giving up on this in the past because it misbehaved, but I cannot reproduce the problem in this case. The docs claim that it just dynamically takes the type of the current class, which seems safe. Let's try this then.