Obsolete the <param> element

[domenic]

Given that plugins are gone from the web platform (with their full removal from the spec being tracked in #6003), it is not useful. In some browsers it can be used to figure out the URL of an <object>, even when that <object> is not being used for a plugin, via params named "movie", "src", "code", "data", or "url". But we decided to remove this behavior from browsers instead of specifying it.

This retains the HTMLParamElement interface, as well as the parser behavior of <param>.

Closes #387. Helps with #6003.

• At least two implementers are interested (and none opposed):
  • Gecko does not process param at all
  • Chromium is willing to try this removal (i.e. try not handling special-named params).
• Tests are written and can be reviewed and commented upon at:
  • Add a feature to deprecate <param> URL inside <object> web-platform-tests/wpt#33624
• Implementation bugs are filed:
  • Chrome: https://bugs.chromium.org/p/chromium/issues/detail?id=1315717
  • Firefox: https://bugzilla.mozilla.org/show_bug.cgi?id=1774438
  • Safari: https://bugs.webkit.org/show_bug.cgi?id=239188

(See WHATWG Working Mode: Changes for more details.)

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/embedded-content-other.html ( diff )
/iframe-embed-object.html ( diff )
/image-maps.html ( diff )
/index.html ( diff )
/indices.html ( diff )
/media.html ( diff )
/obsolete.html ( diff )
/parsing.html ( diff )
/syntax.html ( diff )
/tables.html ( diff )
/xhtml.html ( diff )

[mfreed7]

Are there statements of support from other implementers somewhere? Gecko sounds supportive but it'd be great to have something more concrete. I haven't seen any comments from WebKit folks, but maybe I missed it.

[domenic]

Well Gecko doesn't implement anything with param at all. I checked their code. So I think we're in good shape there.

Indeed comments from WebKit would be great. Maybe the bug filed will help.

[mtrootyy]

At least one of either the data attribute or the type attribute must be present.
If the itemprop attribute is specified on an object element, then the data attribute must also be specified.

The above should be fixed the following;

The data attribute must be present.

If object element have no param element and no data attribute, object element have no resource.

[domenic]

Thanks @mtrootyy, fixed!

[annevk]

This looks good, thanks for tackling this!

Some of the new advice will be obsolete soon (given the inevitable demise of conforming embed and object), but I don't have concrete suggestions on how to avoid that.

[dbaron]

There is currently some Gecko code for <param> in nsObjectLoadingContent. That said, I think the exposure of the results of this code on HTMLObjectElement and HTMLEmbedElement is [ChromeOnly].

[annevk]

Thank you! I filed https://bugzilla.mozilla.org/show_bug.cgi?id=1774438 on that.