dropdown.js

(function ($) {

  // Add posibility to scroll to selected option
  // usefull for select for example
  $.fn.scrollTo = function(elem) {
    $(this).scrollTop($(this).scrollTop() - $(this).offset().top + $(elem).offset().top);
    return this;
  };

  $.fn.dropdown = function (options) {
    var defaults = {
      inDuration: 300,
      outDuration: 225,
      constrain_width: true, // Constrains width of dropdown to the activator
      hover: false,
      gutter: 0, // Spacing from edge
      belowOrigin: false
    }

    options = $.extend(defaults, options);
    this.each(function(){
    var origin = $(this);

    // Dropdown menu
    var activates = $("#"+ origin.attr('data-activates'));

    function updateOptions() {
      if (origin.data('induration') != undefined)
        options.inDuration = origin.data('inDuration');
      if (origin.data('outduration') != undefined)
        options.outDuration = origin.data('outDuration');
      if (origin.data('constrainwidth') != undefined)
        options.constrain_width = origin.data('constrainwidth');
      if (origin.data('hover') != undefined)
        options.hover = origin.data('hover');
      if (origin.data('gutter') != undefined)
        options.gutter = origin.data('gutter');
      if (origin.data('beloworigin') != undefined)
        options.belowOrigin = origin.data('beloworigin');
    }

    updateOptions();

    // Move Dropdown menu to body. This allows for absolute positioning to work
    if ( !(activates.parent().is($('body'))) ) {
      activates.detach();
      $('body').append(activates);
    }

    var dropdownRealHeight = activates.height();

    /*
      Helper function to position and resize dropdown.
      Used in hover and click handler.
    */
    function placeDropdown() {
      // Check html data attributes
      updateOptions();

      if (options.constrain_width == true) {
        activates.css('width', origin.outerWidth());
      }
      var offset = 0;
      if (options.belowOrigin == true) {
        offset = origin.height();
      }

      // Handle edge alignment
      var offsetLeft = origin.offset().left;

      var width_difference = 0;
      var gutter_spacing = options.gutter;

      if (offsetLeft + activates.innerWidth() > $(window).width()) {
        width_difference = origin.innerWidth() - activates.innerWidth();
        gutter_spacing = gutter_spacing * -1;
      }
      if (elementOrParentIsFixed(origin[0])) {
        activates.css({
          display: 'block',
          position: 'fixed',
          height: 0,
          top: origin.offset().top - $(window).scrollTop() + offset,
          left: origin.offset().left + width_difference + gutter_spacing
        });
      }
      else {
        activates.css({
          display: 'block',
          top: origin.offset().top + offset,
          left: origin.offset().left + width_difference + gutter_spacing,
          height: 0
        });
      }
      activates.velocity({opacity: 1}, {duration: options.inDuration, queue: false, easing: 'easeOutQuad'})
      .velocity(
      {
        height: dropdownRealHeight
      },
      {duration: options.inDuration,
        queue: false,
        easing: 'easeOutCubic',
        complete: function(){
          activates.css('overflow-y', 'auto')
        }
      });
    }
    function elementOrParentIsFixed(element) {
        var $element = $(element);
        var $checkElements = $element.add($element.parents());
        var isFixed = false;
        $checkElements.each(function(){
            if ($(this).css("position") === "fixed") {
                isFixed = true;
                return false;
            }
        });
        return isFixed;
    }

    function hideDropdown() {
      activates.velocity(
        {
          opacity: 0
        },
        {
          duration: options.outDuration,
          easing: 'easeOutQuad',
          complete: function(){
            activates.css({
              display: 'none',
              'overflow-y': ''
            });
          }
        });
    }

    // Hover
    if (options.hover) {
      // Hover handler to show dropdown
      origin.on('mouseover', function(e){ // Mouse over
        placeDropdown();
      });

      // Document click handler
      activates.on('mouseleave', function(e){ // Mouse out
        hideDropdown();
      });

    // Click
    } else {
      var open = false;

      // Click handler to show dropdown
      origin.unbind('click.' + origin.attr('id'));
      origin.bind('click.'+origin.attr('id'), function(e){
        if (origin[0] == e.currentTarget) {

          e.preventDefault(); // Prevents button click from moving window
          placeDropdown();
        }

        $(document).bind('click.'+ activates.attr('id'), function (e) {
          if (!activates.is(e.target) && !origin.is(e.target) && (!origin.find(e.target).length > 0) ) {
            hideDropdown();
            $(document).unbind('click.' + activates.attr('id'));
          }
        });
      });

    } // End else

    // Listen to open and close event - useful for select component
    origin.on('open', placeDropdown);
    origin.on('close', hideDropdown);


   });
  }; // End dropdown plugin

  $(document).ready(function(){
    $('.dropdown-button').dropdown();
  });
}( jQuery ));