`writable` values of `Symbol.toStringTag` property of `DOMIterables` are overwritten to `true`

[canalun]

Hi, core-js team. Thank you for developing this great library.

Background

packages/core-js-pure/override/modules/web.dom-collections.iterator.js sets writable of Symbol.toStringTag property of DOM Iterables as true. That is because createNonEnumerableProperty() defines PropertyDescriptor with writable: true.

As a result, the presence or absence of core-js affects some systems whose behavior changes depending on the writable value. For example, this part of lodash will be affected.

Question

1. What is the reason for overwrite of the writable value of Symbol.toStringTag property of DOM Iterables? (I'm thinking about patching to stop this overwrite on my application using core-js. Of course, if I can help anything, I'd like to contribute to core-js also.)
2. This file, packages/core-js-pure/override/modules/web.dom-collections.iterator.js, is in core-js-pure. I've thought that core-js will never overwrite prototypes. It's not correct??

[zloirock]

Thanks, you are right, they should be non-writable.

Could you show for what collections and in what engines they are defined? With the current logic, they should be defined only in case of lack or inconsistency @@toStringTag on DOM collections prototypes.

[canalun]

Thanks :)

• Engine: V8 11.9.169.6 (Chrome v119.0.6045.159)
• Collections whose writable of Symbol.toStringTag property is changed: as follows

  CSSRuleList
  CSSStyleDeclaration
  DOMRectList
  DOMStringList
  DOMTokenList
  DataTransferItemList
  FileList
  HTMLAllCollection
  HTMLCollection
  HTMLFormElement
  HTMLSelectElement
  MediaList
  MimeTypeArray
  NamedNodeMap
  NodeList
  Plugin
  PluginArray
  SVGLengthList
  SVGNumberList
  SVGPointList
  SVGStringList
  SVGTransformList
  SourceBufferList
  StyleSheetList
  TextTrackCueList
  TextTrackList
  TouchList

I checked by using the below page. https://codesandbox.io/p/sandbox/determined-bose-sk7wqw

[zloirock]

Ok, thanks, here is a wrong condition.

[zloirock]

classof(CollectionPrototype) !== TO_STRING_TAG instead of classof(CollectionPrototype) !== COLLECTION_NAME

[canalun]

Got it, thanks :) I'll try to patch it!

[zloirock]

Here also required some other changes, I already made them -)

[canalun]

wow, really thanks...!! I'm trying it on my environment now :)

[canalun]

The problem has been resolved, thank you so much for your quick response! ! !