# ally.is.onlyTabbable

Determines if an element is considered tabbable and not focusable.

# Description

An element is considered tabbable and not focusable if the element is part of the document's focus navigation sequence, but cannot be focused by script.

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

# Usage

var element = document.getElementById('victim');
var isOnlyTabbable = ally.is.onlyTabbable(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.onlyTabbable.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 only tabbable.

# Throws

TypeError if element argument is not of type HTMLElement.

# Changes

Since v1.1.0 all <object> elements in Internet Explorer are not considered only tabbable anymore.
Since v1.1.0 exceptions can be passed to ally.is.onlyTabbable.rules(options).
Since v1.1.0 the state of the <iframe> or <object> element in which the currently examined element is hosted in is considered.
Since v1.1.0 elements must be visible to be considered only tabbable.
Since v1.4.0 SVG elements are no longer considered only tabbable in IE9+, Edge12+ and Firefox 51+.

# Notes

See ally.is.focusRelevant

There is no way to feature detect if an element is tabbable or not. The Element.tabIndex property gives some indication, but ultimately user agent sniffing (via platform.js) is done internally to fix mismatches.

Even though SVG elements are focusable by script in Internet Explorer, they may lack the .focus() and .blur() methods. In order to safely manage focus for these elements use ally.element.focus and ally.element.blur.

ally.is.focusRelevant is used to identify elements that can receive focus
ally.is.focusable identifies focusable elements
ally.is.tabbable identifies keyboard focusable elements
What Browsers Consider Focusable
What ally.js fails to consider focusable