* Executes a given operation type. * @param {String} type * @return {Boolean}

* Helper function to retrieve attribute value. * @param {String} suffix * @param {Element} element

* Helper function for legacy browsers and iframes which sometimes focus * elements like document, body, and non-interactive SVG. * @param {Eleme

* Add the `focus-visible` class to the given element if it was not added by * the author. * @param {Element} el

* Add a group of listeners to detect usage of any pointing devices. * These listeners will be added when the polyfill first loads, and anytime *

* Delegates event to a selector. * * @param {Element} element * @param {String} selector * @param {String}

* Finds the closest parent that matches a selector. * * @param {Element} element * @param {String} selector

* Creates a fake textarea element with a value. * @param {String} value * @return {HTMLElement}

* Delegates event to a selector. * * @param {Element|String|Array} [elements] * @param {String} selector *

* Computes whether the given element should automatically trigger the * `focus-visible` class being added, i.e. whether it should always match *

* Adds an event listener to a HTML element * and returns a remove listener function. * * @param {HTMLElement} node

* Add an event listener to a list of HTML elements * and returns a remove listener function. * * @param {NodeList|HTM

* Add an event listener to a selector * and returns a remove listener function. * * @param {String} selector

* Subscription when the DOM is ready * @param {Function} callback

* Remove the `focus-visible` class from the given element if it was not * originally added by the author. * @param {Element} el

* @param {String|HTMLElement|HTMLCollection|NodeList} trigger * @param {Object} options

* https://github.com/WICG/focus-visible

* Validates all params and calls the right * listener function based on its target type. * * @param {String|HTMLEleme

* Finds closest match and invokes callback. * * @param {Element} element * @param {String} selector * @par

* Callback wrapper for check loaded state

* On `blur`, remove the `focus-visible` class from the target. * @param {Event} e

* On `focus`, add the `focus-visible` class to the target if: * - the target received focus as a result of keyboard navigation, or * - the event

* When the polfyill first loads, assume the user is in keyboard modality. * If any event is received from a pointing device (e.g. mouse, pointer,

* Treat `keydown` as a signal that the user is in keyboard modality. * Apply `focus-visible` to any current active element and keep track * of o

* If at any point a user clicks with a pointing device, ensure that we change * the modality away from keyboard. * This avoids the situation whe

* If the user changes tabs, keep track of whether or not the previously * focused element had .focus-visible. * @param {Event} e