🔗ally.is.focusRelevant

Determines if an element has any relevance to focus management.

🔗Description

This module is a pre-filter for ally.is.focusable, ally.is.tabbable, ally.is.onlyTabbable and ally.get.focusRedirectTarget. Elements may be considered focus-relevant, even though they do not in fact be focusable, tabbable, only-tabbable or redirect focus given their current conditions. But any element that is focusable, tabbable, only-tabbable or redirects focus is focus-relevant.

Consult the data tables what browsers consider focusable and what ally.js considers focusable to learn how HTML elements behave.

🔗Usage

var element = document.getElementById('victim');
var isFocusRelevant = ally.is.focusRelevant(element);

🔗Arguments

Name	Type	Default	Description
element	`HTMLElement`	required	The Element to test.

The underlying rules can also be accessed in the options argument style by calling ally.is.focusRelevant.rules(options):

Name	Type	Default	Description
context	`<selector>`	required	The element to examine. The first element of a collection is used.
except	`<focus identification exception>`	`{}`	The Element to test.

🔗Returns

Boolean, true if the element is focus relevant.

🔗Throws

TypeError if element argument is not of type HTMLElement.

🔗Changes

Since v#master the <embed> and <keygen> elements are considered focus-relevant, but not focusable.
Since v#master the element.prototype.matches polyfill is re-applied to allow elements from other documents (e.g. from an iframe).
Since v#master the <object> element properly distinguishes between SVG and SWF content.
Since v#master elements using Flexbox layout are properly identified in IE10 and IE11.
Since v#master the Shadow DOM hosts are considered focus-relevant, but not focusable.
Since v#master scrollable containers are properly identified in Internet Explorer.
Since v#master all <area> elements are considered focus-relevant.
Since v#master every element that is either focusable, keyboard focusable, only tabbable or redirects focus is considered focus-relevant.
Since v#master exceptions can be passed to ally.is.focusRelevant.rules(options).
Since v#master IE9 properly resolves SVG links (<a xlink:href="…">).

🔗Notes

NOTE: The <body> element may mistakenly considered focusable, because it is the default activeElement if no other element has focus - but it is not focusable, unless made so by adding the tabindex attribute.

NOTE: Because the <keygen> element is poorly supported, practically never used and has seen intent to deprecate, ally considers all <keygen> elements focus-relevant but not focusable.

NOTE: Because the behavior of the <embed> element depends on the content type and browser plugin, ally considers all <embed> elements focus-relevant but not focusable.

WARNING: Firefox and Internet Explorer cannot focus SVGElements by script, thus no SVG element is considered focusable, see Gecko 1116966

WARNING: WebKit and Blink make any SVGElement focusable that has a focus event listener attached, see Blink 445798, WebKit 140024

🔗Related resources

ally.is.focusable tests focus-relevant elements if they're also visible and not disabled
ally.is.tabbable tests elements if they're keyboard focusable
ally.is.validTabindex is used to verify the element's tabindex value is valid
ally.query.focusable finds focusable elements in the DOM
What Browsers Consider Focusable
What ally.js Considers Focusable