Array.from should not touch Array.prototype setters (createDataPropertyOrThrow)

[Yaffle]

An edge case...

Object.defineProperty(Object.prototype, "0", {
  set: function () {
    throw new Error();
  },
  get: function () {
    return undefined;
  }
});

Array.from({length: 1}); // should not throw here

[Yaffle]

Ah... this was fixed in https://github.com/mathiasbynens/Array.from ... sorry

[ljharb]

Hmm, there's no fix for this in https://github.com/mathiasbynens/Array.from or this repo at all?

However, according to https://tc39.github.io/ecma262/#sec-array.from step 12.b., it seems like it should indeed throw in this case.

[Yaffle]

What about step 12.e ?

[ljharb]

Ah, you're correct that step 12e is what applies here - but the ? in the spec means if CreateDataPropertyOrThrow returns an abrupt completion, that the exception should be thrown.

[Yaffle]

OK

[Yaffle]

@ljharb The setter will not be touched with CreateDataPropertyOrThrow.

[ljharb]

Good call, you're totally correct. Thanks for clarifying.