Error on a constant declaration for HTMLAudioElement

[dascritch]

When I have an audiotag typed as an HTMLAudioElement, and i'm checking audiotag.readyState < audiotag.HAVE_CURRENT_DATA , closure in ADVANCED_OPTIMIZATIONS mode doesn't like it :

WARNING - [JSC_INEXISTENT_PROPERTY] Property HAVE_CURRENT_DATA never defined on HTMLAudioElement

As I'm reading, HAVE_CURRENT_DATA is defined here : https://github.com/google/closure-compiler/blob/master/externs/browser/html5.js#L1944
But not on HTMLMediaElement.prototype . So we cannot even use HTMLAudioElement.HAVE_CURRENT_DATA.

As I can read in https://developer.mozilla.org/en-US/docs/Web/API/HTMLAudioElement :

inherits properties from its parent, HTMLMediaElement, and from HTMLElement. 

Perhaps I'm wrong, but as any browsers is accepting my audiotag.HAVE_CURRENT_DATA, may be those declarations must be changed into :

HTMLMediaElement.prototype.HAVE_CURRENT_DATA;

[kjin]

Created Google internal issue http://b/143219987

[kjin]

Is there any particular reason you can't write it as audiotag.readyState < HTMLMediaElement.HAVE_CURRENT_DATA? It's true that in browsers you can access it on any of HTMLMediaElement or its subclasses' definitions or prototypes, but given that it is a constant, would make more sense to access it as a static property of the base class itself?

[dascritch]

Hi @kjin.
Honestly, no, there is no technical reason, except losing some chars in the outputted minified JS, as we will have :

a.readyState<HTMLMediaElement.HAVE_CURRENT_DATA

instead of

a.readyState<a.HAVE_CURRENT_DATA

It may count when I have lots of references to this kind of constants.

I know, this is really ugly and over-engineering

[dascritch]

Funnily... The warning doesn't trigger in some cases :

As today, I have to write it there
https://github.com/dascritch/cpu-audio/blob/57bacdd06071fff362b311d7ca18cabc9d3665b8/src/40_document_cpu.js#L247

But the warning won't trigger there
https://github.com/dascritch/cpu-audio/blob/57bacdd06071fff362b311d7ca18cabc9d3665b8/src/45_element_cpu.js#L82

[kjin]

Ah, got it. I do see that the HTML5 externs file does contain existing examples where constants exist on both a class and its prototype (like WebSocket) so this doesn't seem like an unprecedented change, it seems doable.

[kjin]

I've landed a change to add all of the constants on HTMLMediaElement to its prototype as well ( (should work for instances of type HTMLAudioElement too), and it should be in the next compiler release.