Iterator.prototype.constructor

[zloirock]

Now it's Object, maybe it should be Iterator?

[zloirock]

Theoretically, it could be a breaking change since could affect some old code:

[].values().constructor; // => Object

but unlikely that someone used it.

[michaelficarra]

Can you give some examples of why it would be useful to do this?

[ljharb]

Because [].values() instanceof Iterator should be true.

[zloirock]

JS objects contain .constructor and if it's already a part of the objects model, we should not forget about. Someone uses it for identification of objects, someone for subclassing. I'm not a fan of active usage of this property, but since some libraries and developers use it...

[michaelficarra]

@ljharb Iterator[@@hasInstance]?

[devsnek]

OrdinaryHasInstance of o and C uses C.prototype, not o.constructor. That being said, I don't really see any reason not to update the constructor property. I seriously doubt it would break anyone.

[michaelficarra]

Okay so is there any tangible benefit to making this change? Is it just for consistency?

[zloirock]

@michaelficarra since we must respect the concepts that are already used in the language?

[ljharb]

Consistency is a tangible benefit.

(yes, Symbol.hasInstance would help, but why when we could fix the prototype and the constructor)

[zloirock]

@ljharb @@hasInstance is not required, the prototype already added and your example already works with this proposal.