abstract class prototype type has abstract methods even though they are not on the prototype

[Pmyl]

Bug Report

🔎 Search Terms

abstract, prototype, type

🕗 Version & Regression Information

All versions I tried

⏯ Playground Link

Playground link with relevant code

💻 Code

abstract class AnAbstract {
  public abstract abstractMethod(): void;

  public nonAbstractMethod(): void {
    // do something
  }
}

// no type error - undefined
console.log(AnAbstract.prototype.abstractMethod);
// no type error - false
console.log(AnAbstract.prototype.hasOwnProperty('abstractMethod'));

// defined
console.log(AnAbstract.prototype.nonAbstractMethod);
// true
console.log(AnAbstract.prototype.hasOwnProperty('nonAbstractMethod'));

🙁 Actual behavior

Abstract class prototype has abstract methods in the type

🙂 Expected behavior

Abstract class prototype to have only concrete methods in the type

---

I have a function that manually define methods based on what's in the prototype, unfortunately when I use an abstract class the type doesn't reflect reality.

If that type cannot change it would be great to be able to do something like:

type NoAbstract<T> = {
  -abstract [key in keyof T]: T[key];
};

[RyanCavanaugh]

prototype also has instance properties (which is similarly wrong). We needed that for some assignability reasons I don't recall, but might be able to modify this behavior if it comes up often enough in practice.