- From: Brian Birtles via GitHub <sysbot+gh@w3.org>
- Date: Thu, 10 Sep 2020 23:05:04 +0000
- To: public-css-archive@w3.org
> `iterations` and `duration` are expected to not be `NaN`, but not `iterationStart`. Is there a reason for this or is it just missing?
Yes, `iterations` and `duration` have type [`unrestricted double`](https://heycam.github.io/webidl/#idl-unrestricted-double) so they can take values like `Infinity` and `NaN`. That's because those values need to be able to represent infinity.
`iterationStart`, however, has type `double` so it can't take such values. Validation that `iterationStart` is not `NaN` happens at the WebIDL binding layer and so no additional spec text is required.
> ```js
> new KeyframeEffect($0, { opacity: [0, 1] }, { iterations: NaN })
> // Uncaught TypeError: Failed to construct 'KeyframeEffect': iterationCount must be non-negative
> ```
(That's odd that Chrome reports an error for `iterationCount` when validating `iterations`.)
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Received on Thursday, 10 September 2020 23:05:06 UTC