[css-animations-1] CSSKeyframesRule should have index getter

[rniwa]

Blink and WebKit has index getter on CSSKeyframesRule. For best interoperability, I recommend adding it to the spec.

See WebKit's IDL for example:

[
    Exposed=Window
] interface CSSKeyframesRule : CSSRule {
    attribute [AtomString] DOMString name;
    readonly attribute CSSRuleList cssRules;
    
    undefined insertRule(DOMString rule);
    undefined appendRule(DOMString rule);
    undefined deleteRule(DOMString key);
    CSSKeyframeRule? findRule(DOMString key);

    getter CSSKeyframeRule (unsigned long index);
};

[birtles]

According to the WebIDL spec,

Interfaces that support indexed properties must define an integer-typed attribute named "length".

I think the change needs to be:

[Exposed=Window]
interface CSSKeyframesRule : CSSRule {
           attribute CSSOMString name;
  readonly attribute CSSRuleList cssRules;

+  getter CSSKeyframeRule (unsigned long index);
+  readonly attribute unsigned long length;

  undefined        appendRule(CSSOMString rule);
  undefined        deleteRule(CSSOMString select);
  CSSKeyframeRule? findRule(CSSOMString select);
};

I'm happy to do that and add the necessary WPT if no one objects.

As for insertRule, it doesn't appear to be in Gecko or Blink so I suppose either Webkit should drop it or file a separate issue for adding it?

[cdoublev]

I am a bit late but I assume the expected rule's order is the order of appearance in @keyframes, isn't it? Maybe it would have been usefull to sort them by start time, and fallback to appearance order when two rules have the same start time.

[birtles]

I am a bit late but I assume the expected rule's order is the order of appearance in @keyframes, isn't it?

I think so. It's basically just an alias for cssRules.