jquery-ui.tabbable-focusable.js

(function ($) {
  /**
   * jQuery extension: Add support for :tabbable and :focusable pseudo-classes
   */
  $.extend($.expr[':'], {
    data: $.expr.createPseudo
      ? // creating pseudo's supported?
      $.expr.createPseudo(function(dataName) {
        return function(elem) {
          return !!$.data(elem, dataName);
        };
      })
      : // otherwise (supports jQuery <1.8)
      function(elem, i, match) {
        return !!$.data(elem, match[3]);
      },

    focusable: function(element) {
      return focusable(element, !isNaN($.attr(element, 'tabindex')));
    },

    tabbable: function(element) {
      var tabIndex = $.attr(element, 'tabindex'),
          isTabIndexNaN = isNaN(tabIndex);
      return (isTabIndexNaN || tabIndex >= 0) && focusable(element, !isTabIndexNaN);
    }
  });
  /**
   * focussable() function, taken from jQuery UI Core
   * @param element
   * @returns {*}
   */
  function focusable(element) {
    var map, mapName, img,
        nodeName = element.nodeName.toLowerCase(),
        isTabIndexNotNaN = !isNaN($.attr(element, 'tabindex'));

    if ('area' === nodeName) {
      map = element.parentNode;
      mapName = map.name;
      if (!element.href || !mapName || map.nodeName.toLowerCase() !== 'map') {
        return false;
      }
      img = $('img[usemap=#' + mapName + ']')[0];
      return !!img && visible(img);
    }

    return (/^(input|select|textarea|button|object)$/.test(nodeName)
      ? !element.disabled
      : ('a' === nodeName
          ? element.href || isTabIndexNotNaN
          : isTabIndexNotNaN
        )
      ) &&
      // the element and all of its ancestors must be visible
      visible(element);

    function visible(element) {
      return $.expr.filters.visible(element) &&
        !$(element).parents().addBack().filter(function() {
          return $.css(this, 'visibility') === 'hidden';
        }).length;
    }
  }

})(window.jQuery);