[css-houdini-drafts] [css-properties-values-api] mention how animations involving invalid token stream values work

heycam has just created a new issue for 
https://github.com/w3c/css-houdini-drafts:

== [css-properties-values-api] mention how animations involving 
invalid token stream values work ==
Imagine a transition that involves an invalid token stream value:

```html
<style>
p { transition: --test 1s; }
p:hover { --test: something; }
</style>
<p>hover me</p>
```

When you hover over the `<p>`, it should generate a transition from 
the underyling value, which is the initial value -- the special 
invalid token stream value -- to the token stream `" something"`.  I 
think this should be valid, and, since it's a token stream typed 
custom property, and therefore not interpolable, will switch value at 
0.5s.

Similarly in the other direction:

```html
<style>
p { transition: --test 1s; --test: something; }
p:hover { --test: var(--test); }
</style>
<p>hover me</p>
```

Here the initial, underyling value is the token stream `" something"` 
and the end value is the special invalid token stream value.

I think it makes sense that animations involving the special invalid 
token stream values work, but it would be good to call this case out 
specially in the spec somewhere.

@birtles @jyc 

Please view or discuss this issue at 
https://github.com/w3c/css-houdini-drafts/issues/285 using your GitHub
 account

Received on Wednesday, 24 August 2016 06:42:22 UTC