On Fri, Sep 20, 2013 at 1:58 PM, Simon Pieters <simonp@opera.com> wrote: > On Fri, 20 Sep 2013 19:40:48 +0200, Glenn Adams <glenn@skynav.com> wrote: > > The argument was that if authors expect `cue instanceof RawCue` to mean >>> that the UA doesn't render it, we shouldn't break that expectation. It >>> doesn't matter that there are other ways to check it. For instance, you >>> could do cue.__proto__ == RawCue.prototype. >>> >>> >> Backward compatibility with current usage doesn't seem to be a strong >> consideration here given other changes being made, e.g., removing >> TextTrackCue constructor. >> > > Right, but we're discussing expectations, not back compat. > > Case study: HTMLUnknownElement is used for HTML elements that the UA > doesn't support but still exposes in the DOM. It inherits from HTMLElement. > Elements that the UA supports inherits from HTMLElement (or uses > HTMLElement), they never inherit from HTMLUnknownElement. That analogy may hold for out-of-band track MIME types unrecognized by the UA, however, it doesn't hold for in-band tracks where the UA is at least able to extract content, including possible decoding of bytes into UTF-16 encoding units (for representation in a DOMString) or into BASE64, but the UA doesn't take any further action (perhaps because it doesn't support rendering a renderable @kind).
Received on Friday, 20 September 2013 20:05:57 UTC