Spinbutton Pattern: Add aria-invalid guidance for values outside allowed range

[mcking65]

In response to issue #704, modified the roles, states, and properties section of the spinbutton pattern in aria-practices.html.

Adds a bullet to the list of roles, states, and properties stating that aria-invalid is set true if it is possible for the textbox to contain a value that is not allowed.

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Preview | Diff

[0ddfell0w]

Thanks for the change, my only note is that the wording could be misconstrued (with some effort) to be saying "if an invalid state is possible then set aria-invalid to true" as opposed to "For spinbuttons that allow users to enter invalid inputs, set aria-invalid to true when the value is invalid."

[mcking65]

@0ddfell0w, Commit 02bb24f changes the wording to:

The spinbutton element has aria-invalid set to true if the value is outside the allowed range. Note that most implementations prevent input of invalid values, but in some scenarios, blocking all invalid input may not be practical.

[charmarkk]

This looks good to me Matt! -Mark

[ZoeBijl]

How about something like this:

Most spinbutton implementations will prevent the input of invalid values. But, in some cases blocking invalid input might not be practical. In such scenarios aria-invalid is set to true if the value is outside of the allowed range.

This is pretty close to how I’d write it in an article or some such. I think I kept the information the same and only changed the tone slightly.