[wp-trac] [WordPress Trac] #47975: Prevent aria-described broken reference in `comment_form()`

[WordPress Trac]

#47975: Prevent aria-described broken reference in `comment_form()`
-------------------------------------+-----------------------------
 Reporter:  afercia                  |      Owner:  (none)
     Type:  defect (bug)             |     Status:  new
 Priority:  normal                   |  Milestone:  Awaiting Review
Component:  Comments                 |    Version:
 Severity:  normal                   |   Keywords:
  Focuses:  accessibility, template  |
-------------------------------------+-----------------------------
 The `comment_form()` generates a complete commenting form, mainly used by
 themes.

 The email field markup has an `aria-describedby="email-notes"` attribute
 that targets a description. Actually the description is the default
 `comment_notes_before` argument and outputs the following HTML (simplified
 code):


 {{{
 <p class="comment-notes"><span id="email-notes">Your email address will
 not be published.</span></p>
 }}}


 However, it is possible to pass the `comment_notes_before` a completely
 different HTML (which may ''not'' contain the `email-notes` ID) or an
 empty string to completely omit the description. See for example the
 comment form on this page:

 https://andersnoren.se/themes/chaplin/2014/08/03/babela-armchair/

 It's understandable developers are misled: the `comment_form()` function
 allows to do this, while it should ensure semantic markup. I'd tend to
 think this is a core responsibility that can't be delegated to the
 developers attention to details.

 In these cases, the `aria-describedby` attribute points to a broken
 reference. This should be avoided because the attribute communicates user
 agents and assistive technologies there's a description but then the
 referenced description is missing. It will be flagged as failure by any
 accessibility automated checker tool and, most importantly, is potentially
 confusing for assistive technologies users.

 Related standard:
 https://www.w3.org/TR/WCAG21/#info-and-relationships

 Ideally, the `aria-describedby` attribute should be printed out only if
 there's a description and only if the targeted ID actually exists. One
 option could be checking for a non empty `comment_notes_before` and wrap
 an element with ID `email-notes` around its output.

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Ticket URL: <https://core.trac.wordpress.org/ticket/47975>
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