[csswg-drafts] [web-animations-1] Don't throw for custom iterator that return null/undefined

stephenmcgruer has just created a new issue for https://github.com/w3c/csswg-drafts:

== [web-animations-1] Don't throw for custom iterator that return null/undefined ==
(From discussion on https://github.com/w3c/web-platform-tests/pull/10399)

Currently the procedure to process a keyframes argument (https://drafts.csswg.org/web-animations-1/#processing-a-keyframes-argument) says:

(in the otherwise case)
5.4.6 "If nextItem is not an object, throw a TypeError and abort these steps."

However in the above linked PR, Brian noted:

"Yeah, it looks like we shouldn't throw on null / undefined.

In WebIDL when we [create a sequence from an iterable](https://heycam.github.io/webidl/#create-sequence-from-iterable) we have the step:

> 4. Initialize Si to the result of converting nextItem to an IDL value of type T.

For [converting dictionary types](https://heycam.github.io/webidl/#es-dictionary) we have:

> 1. If Type(V) is not Undefined, Null or Object, then throw a TypeError.

So we should update the Web Animations spec to match this and add a test for this case that we don't throw."

Please view or discuss this issue at https://github.com/w3c/csswg-drafts/issues/2533 using your GitHub account

Received on Wednesday, 11 April 2018 11:39:18 UTC