Rethink enumerability hack for symbols

[medikoo]

Currently naturally set symbol properties (via e.g. x[symbol] = 'foo') are defined under the hood as not enumerable, so they're hidden from Object.keys and for in iterations.

This however has side effect of symbols not being copied as expected via Object.assign and incorrect value being returned for obj.propertyIsEnumerable(symbol).

Fix would be, to make them naturally enumerable (resign from Object.prototype hack), but update Object.keys shim within es5-ext project so it will filter eventual symbols created by polyfill. Additionally for .. in counterpart can be provided as well.

[WebReflection]

FYI I've solved this in https://github.com/WebReflection/get-own-property-symbols

[WebReflection]

early comment, sorry.

You cannot make them enumerable because for/in will show them. symbols in ES5 make sense only if assigned as non enumerable, but other methods that deal with descriptors should be aware of the poly.

I've patched propertyIsEnumerable together with defineProperty and defineProperties and now my polyfill works well with Object.assign native or polyfilled.

You can still set non enumerable Symbols when you use defineProperty/ies

[medikoo]

@WebReflection thanks for comment.

Yes as for/in can't be patched, the way you propose, is the only way to get it right

[WebReflection]

forgot to mention that I obviously had to patch Object.getOwnPropertyDescriptor which will return true by default, unless the Symbol hasn't been assigned via defineProperty/ies as non enumerable.

It's a mess but it works :D