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,
      constrainWidth: true, // Constrains width of dropdown to the activator
      hover: false,
      gutter: 0, // Spacing from edge
      belowOrigin: false,
      alignment: 'left',
      stopPropagation: false
    };

    // Open dropdown.
    if (options === "open") {
      this.each(function() {
        $(this).trigger('open');
      });
      return false;
    }

    // Close dropdown.
    if (options === "close") {
      this.each(function() {
        $(this).trigger('close');
      });
      return false;
    }

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

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

      function updateOptions() {
        if (origin.data('induration') !== undefined)
          curr_options.inDuration = origin.data('induration');
        if (origin.data('outduration') !== undefined)
          curr_options.outDuration = origin.data('outduration');
        if (origin.data('constrainwidth') !== undefined)
          curr_options.constrainWidth = origin.data('constrainwidth');
        if (origin.data('hover') !== undefined)
          curr_options.hover = origin.data('hover');
        if (origin.data('gutter') !== undefined)
          curr_options.gutter = origin.data('gutter');
        if (origin.data('beloworigin') !== undefined)
          curr_options.belowOrigin = origin.data('beloworigin');
        if (origin.data('alignment') !== undefined)
          curr_options.alignment = origin.data('alignment');
        if (origin.data('stoppropagation') !== undefined)
          curr_options.stopPropagation = origin.data('stoppropagation');
      }

      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');

        var originWidth = origin[0].getBoundingClientRect().width;

        // Constrain width
        if (curr_options.constrainWidth === true) {
          activates.css('width', originWidth);

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

        // Offscreen detection
        var windowHeight = window.innerHeight;
        var originHeight = origin.innerHeight();
        var offsetLeft = origin.offset().left;
        var offsetTop = origin.offset().top - $(window).scrollTop();
        var currAlignment = curr_options.alignment;
        var gutterSpacing = 0;
        var leftPosition = 0;

        // Below Origin
        var verticalOffset = 0;
        if (curr_options.belowOrigin === true) {
          verticalOffset = originHeight;
        }

        // Check for scrolling positioned container.
        var scrollYOffset = 0;
        var scrollXOffset = 0;
        var wrapper = origin.parent();
        if (!wrapper.is('body')) {
          if (wrapper[0].scrollHeight > wrapper[0].clientHeight) {
            scrollYOffset = wrapper[0].scrollTop;
          }
          if (wrapper[0].scrollWidth > wrapper[0].clientWidth) {
            scrollXOffset = wrapper[0].scrollLeft;
          }
        }


        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() > windowHeight) {
          // If going upwards still goes offscreen, just crop height of dropdown.
          if (offsetTop + originHeight - activates.innerHeight() < 0) {
            var adjustedHeight = windowHeight - offsetTop - verticalOffset;
            activates.css('max-height', adjustedHeight);
          } else {
            // Flow upwards.
            if (!verticalOffset) {
              verticalOffset += originHeight;
            }
            verticalOffset -= activates.innerHeight();
          }
        }

        // Handle edge alignment
        if (currAlignment === 'left') {
          gutterSpacing = curr_options.gutter;
          leftPosition = origin.position().left + gutterSpacing;
        }
        else if (currAlignment === 'right') {
          // Material icons fix
          activates
            .stop(true, true)
            .css({
              opacity: 0,
              left: 0
            })

          var offsetRight = origin.position().left + originWidth - activates.width();
          gutterSpacing = -curr_options.gutter;
          leftPosition =  offsetRight + gutterSpacing;
        }

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

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

        // Add click close handler to document
        setTimeout(function() {
          $(document).on('click.'+ activates.attr('id'), function (e) {
            hideDropdown();
            $(document).off('click.'+ activates.attr('id'));
          });
        }, 0);
      }

      function hideDropdown() {
        // Check for simultaneous focus and click events.
        isFocused = false;
        activates.fadeOut(curr_options.outDuration);
        activates.removeClass('active');
        origin.removeClass('active');
        $(document).off('click.'+ activates.attr('id'));
        setTimeout(function() { activates.css('max-height', ''); }, curr_options.outDuration);
      }

      // Hover
      if (curr_options.hover) {
        var open = false;
        origin.off('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.off('click.' + origin.attr('id'));
        origin.on('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
              if (curr_options.stopPropagation) {
                e.stopPropagation();
              }
              placeDropdown('click');
            }
            // If origin is clicked and menu is open, close menu
            else if (origin.hasClass('active')) {
              hideDropdown();
              $(document).off('click.'+ 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 ));