- From: Tab Atkins Jr. via GitHub <sysbot+gh@w3.org>
- Date: Fri, 03 Feb 2017 19:38:12 +0000
- To: public-houdini-archive@w3.org
Further clarification: per [Seattle
resolution](https://log.csswg.org/irc.w3.org/houdini/2017-01-10/#e756301),
when using a typed property *in a stylesheet*, setting to an invalid
value doesn't trigger fallback. That is:
```
<script>
CSS.registerProperty("--foo", {grammar: "<color>"});
</script>
<style>
div { --foo: red; }
div.foo { --foo: hello; }
</style>
```
In here, the "--foo: hello" is *not* thrown out at parse-time; it's
accepted, but because it's invalid, it gets treated as "--foo:
unset;".
* This is an intentional break from "real" CSS properties, because the
threat model is different (unpredictable browsers with varying
support, vs known libraries with well-known support).
* This *removes* the order-dependence between setting and registration
when you're setting in a stylesheet, rather than thru the JS API.
* This makes typed custom properties less consistent with "real" CSS
properties, but more consistent with *untyped* custom properties.
--
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Received on Friday, 3 February 2017 19:38:19 UTC