aria-activedescendant-has-tabindex

aria-activedescendant is used to manage focus within a composite widget. The element with the attribute aria-activedescendant retains the active document focus; it indicates which of its child elements has secondary focus by assigning the ID of that element to the value of aria-activedescendant. This pattern is used to build a widget like a search typeahead select list. The search input box retains document focus so that the user can type in the input. If the down arrow key is pressed and a search suggestion is highlighted, the ID of the suggestion element will be applied as the value of aria-activedescendant on the input element.

Because an element with aria-activedescendant must be tabbable, it must either have an inherent tabIndex of zero or declare a tabIndex of zero with the tabIndex attribute.

References

1. MDN

Rule details

This rule takes no arguments.

Succeed

<CustomComponent />
<CustomComponent aria-activedescendant={someID} />
<CustomComponent aria-activedescendant={someID} tabIndex={0} />
<CustomComponent aria-activedescendant={someID} tabIndex={-1} />
<div />
<input />
<div tabIndex={0} />
<div aria-activedescendant={someID} tabIndex={0} />
<div aria-activedescendant={someID} tabIndex="0" />
<div aria-activedescendant={someID} tabIndex={1} />
<input aria-activedescendant={someID} />
<input aria-activedescendant={someID} tabIndex={0} />

Fail

<div aria-activedescendant={someID} />
<div aria-activedescendant={someID} tabIndex={-1} />
<div aria-activedescendant={someID} tabIndex="-1" />
<input aria-activedescendant={someID} tabIndex={-1} />