Standard HTML elements such as <button> or <input> have keyboard accessibility
built in for free. If you're building custom interactive components, however,
use the tabindex attribute to ensure that they're keyboard accessible.
Check if your controls are keyboard accessible
A tool like Lighthouse is great at detecting certain accessibility issues, but some things can only be tested by a human.
Try pressing the Tab key to navigate through your site. Are you able to reach
all the interactive controls on the page? If not, you may need to use
tabindex
to improve the focusability of those controls.
Insert an element into the tab order
Insert an element into the natural tab order using tabindex="0". For example:
<div tabindex="0">Focus me with the TAB key</div>
To focus an element, press the Tab key or call the element's focus() method.
Remove an element from the tab order
Remove an element using tabindex="-1". For example:
<button tabindex="-1">Can't reach me with the TAB key!</button>
This removes an element from the natural tab order, but the element can still be
focused by calling its focus() method.
Note that applying tabindex="-1" to an element doesn't affect its children;
if they're in the tab order naturally or because of a tabindex value,
they'll remain in the tab order.
To remove an element and all its children from the tab order, consider using
the WICG's inert polyfill.
The polyfill emulates the behavior of a proposed inert attribute,
which prevents elements from being selected or read by assistive technologies.
Avoid tabindex > 0
Any tabindex greater than 0 jumps the element to the front of the natural tab
order. If there are multiple elements with a tabindex greater than 0, the tab
order starts from the lowest value greater than zero and works its way up.
Using a tabindex greater than 0 is considered an anti-pattern because
screen readers navigate the page in DOM order, not tab order. If you need an
element to come sooner in the tab order, it should be moved to an earlier spot
in the DOM.
Lighthouse makes it easy to identify elements with a tabindex > 0. Run the
Accessibility Audit (Lighthouse > Options > Accessibility) and look for the
results of the "No element has a [tabindex] value greater than 0" audit.
Create accessible components with "roving tabindex"
If you're building a complex component, you may need to add additional keyboard
support beyond focus. Consider the built-in select element. It is focusable and
you can use the arrow keys to expose additional functionality (the selectable
options).
To implement similar functionality in your own components, use a technique known
as "roving tabindex". Roving tabindex works by setting tabindex to -1 for
all children except the currently-active one. The component then uses a keyboard
event listener to determine which key the user has pressed.
When this happens, the component sets the previously focused child's tabindex
to -1, sets the to-be-focused child's tabindex to 0, and calls the focus()
method on it.
Before
<div role="toolbar">
<button tabindex="-1">Undo</button>
<button tabindex="0">Redo</button>
<button tabindex="-1">Cut</button>
</div>
After
<div role="toolbar">
<button tabindex="-1">Undo</button>
<button tabindex="-1">Redo</button>
<button tabindex="0">Cut</button>
</div>
TODO: DevSite - Think and Check assessment
Keyboard access recipes
If you're unsure what level of keyboard support your custom components might need, you can refer to the ARIA Authoring Practices 1.1. This handy guide lists common UI patterns and identifies which keys your components should support.