HTML and CSS Reference
In-Depth Information
item, itemprop, subject
These attributes are associated with the microdata specifi cation
(see the section “Features not covered in this topic”), which this
book doesn't cover.
role, aria-* attributes
As you've seen, HTML5 treats WAI-ARIA as legal additions to
the language.
This Boolean attribute tells the browser to check the element's
spelling and grammar. If it's missing, “the default state indicates
that the element is to act according to a default behavior, possi-
bly based on the parent element's own spellcheck state.”
tabindex (="-1")
tabindex is a largely archaic concept that allows you to specify
the order in which elements are focused when the user navi-
gates a page with the keyboard (traditionally using the Tab key,
though some browsers—most notably Opera—may use different
key combinations for this).
This used to be quite popular when sites were built using deeply
nested layout tables, but nowadays this is not usually necessary.
The default tab order is determined by the order in which ele-
ments appear in your markup, so a properly ordered and struc-
tured document should never require additional tabbing hints.
However, tabindex does have a useful side-effect. Normally, only
links, form elements, and image map areas can be focused via
the keyboard. Adding a tabindex can make other elements also
focusable, so executing a focus() command from JavaScript
would move the browser's focus to them. However, this would
also make these elements keyboard-focusable, which may not
be desirable.
Using a negative integer (by convention, tabindex=”-1” )
allows the element to be focused programmatically, “but
should not allow the element to be reached using sequential
focus navigation.”
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