materialize-css/js/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 (option) {
    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,
      alignment: 'left'
    };

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

    // 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');
      if (origin.data('alignment') !== undefined)
        options.alignment = origin.data('alignment');
    }

    updateOptions();

    // Attach dropdown to its activator
    origin.after(activates);

    /*
      Helper function to position and resize dropdown.
      Used in hover and click handler.
    */
    function placeDropdown(eventType) {
      // Check for simultaneous focus and click events.
      if (eventType === 'focus') {
        isFocused = true;
      }

      // Check html data attributes
      updateOptions();

      // Set Dropdown state
      activates.addClass('active');
      origin.addClass('active');

      // Constrain width
      if (options.constrain_width === true) {
        activates.css('width', origin.outerWidth());

      } else {
        activates.css('white-space', 'nowrap');
      }

      // Below Origin
      var verticalOffset = 0;
      if (options.belowOrigin === true) {
        verticalOffset = origin.height();
      }

      // Offscreen detection
      var offsetLeft = origin.offset().left;
      var offsetTop = origin.offset().top - $(window).scrollTop();
      var currAlignment = options.alignment;
      var activatesLeft, gutterSpacing;
      if (offsetLeft + activates.innerWidth() > $(window).width()) {
        // Dropdown goes past screen on right, force right alignment
        currAlignment = 'right';

      } else if (offsetLeft - activates.innerWidth() + origin.innerWidth() < 0) {
        // Dropdown goes past screen on left, force left alignment
        currAlignment = 'left';
      }
      // Vertical bottom offscreen detection
      if (offsetTop + activates.innerHeight() > window.innerHeight) {
        if (!verticalOffset) {
          verticalOffset += origin.innerHeight();
        }
        verticalOffset -= activates.innerHeight();
      }

      // Handle edge alignment
      if (currAlignment === 'left') {
        gutterSpacing = options.gutter;
        leftPosition = origin.position().left + gutterSpacing;
      }
      else if (currAlignment === 'right') {
        var offsetRight = origin.position().left + origin.outerWidth() - activates.outerWidth();
        gutterSpacing = -options.gutter;
        leftPosition =  offsetRight + gutterSpacing;
      }

      // Position dropdown
      activates.css({
        position: 'absolute',
        top: origin.position().top + verticalOffset,
        left: leftPosition
      });


      // Show dropdown
      activates.stop(true, true).css('opacity', 0)
        .slideDown({
        queue: false,
        duration: options.inDuration,
        easing: 'easeOutCubic',
        complete: function() {
          $(this).css('height', '');
        }
      })
        .animate( {opacity: 1}, {queue: false, duration: options.inDuration, easing: 'easeOutSine'});
    }

    function hideDropdown() {
      // Check for simultaneous focus and click events.
      isFocused = false;
      activates.fadeOut(options.outDuration);
      activates.removeClass('active');
      origin.removeClass('active');
    }

    // Hover
    if (options.hover) {
      var open = false;
      origin.unbind('click.' + origin.attr('id'));
      // Hover handler to show dropdown
      origin.on('mouseenter', function(e){ // Mouse over
        if (open === false) {
          placeDropdown();
          open = true;
        }
      });
      origin.on('mouseleave', function(e){
        // If hover on origin then to something other than dropdown content, then close
        var toEl = e.toElement || e.relatedTarget; // added browser compatibility for target element
        if(!$(toEl).closest('.dropdown-content').is(activates)) {
          activates.stop(true, true);
          hideDropdown();
          open = false;
        }
      });

      activates.on('mouseleave', function(e){ // Mouse out
        var toEl = e.toElement || e.relatedTarget;
        if(!$(toEl).closest('.dropdown-button').is(origin)) {
          activates.stop(true, true);
          hideDropdown();
          open = false;
        }
      });

    // Click
    } else {
      // Click handler to show dropdown
      origin.unbind('click.' + origin.attr('id'));
      origin.bind('click.'+origin.attr('id'), function(e){
        if (!isFocused) {
          if ( origin[0] == e.currentTarget &&
               !origin.hasClass('active') &&
               ($(e.target).closest('.dropdown-content').length === 0)) {
            e.preventDefault(); // Prevents button click from moving window
            placeDropdown('click');
          }
          // If origin is clicked and menu is open, close menu
          else if (origin.hasClass('active')) {
            hideDropdown();
            $(document).unbind('click.'+ activates.attr('id') + ' touchstart.' + activates.attr('id'));
          }
          // If menu open, add click close handler to document
          if (activates.hasClass('active')) {
            $(document).bind('click.'+ activates.attr('id') + ' touchstart.' + activates.attr('id'), function (e) {
              if (!activates.is(e.target) && !origin.is(e.target) && (!origin.find(e.target).length) ) {
                hideDropdown();
                $(document).unbind('click.'+ activates.attr('id') + ' touchstart.' + activates.attr('id'));
              }
            });
          }
        }
      });

    } // End else

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


   });
  }; // End dropdown plugin

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