Flow: Property not found in HTMLElement / HTMLCollection

[john-gold]

Hey,
can someone please help me to avoid/suppress theses errors? I guess I need to add annotations or change the .flowconfig?

document.querySelector('div#someID > select#anotherID').value = 'newValue';
property value Property not found in HTMLElement

let selects = document.getElementsByTagName('select'); selects.anotherID.value = 'newValue';
property anotherID Property not found in HTMLCollection

[AugustinLF]

The problem is that document.querySelector returns a HTMLElement, which does not necessarily have the property value. You can test for the type of the returned value, by doing, for instance:

const el = document.querySelector('div#someID > select#anotherID')

if (el instanceof HTMLInputElement)
  el.value = 'newValue'

You can also cast the returned value of querySelector to be any, by doing something like (document.querySelector('div#someID > select#anotherID'): any).value = 'newValue'.

But you'll lose all the type checks related to this section.

[aackerman]

@logol I think in this case the declaration of querySelector is wrong. querySelector can return null, or HTMLElement or subtypes of HTMLElement.

Edit: it looks like this is the case from many of the declarations in flow related to the DOM APIs.

[john-gold]

Ah, that explained a lot - thank you very much for your feedback @aackerman @AugustinLF