Template:Edinburgh UG/jqueryScrollUp

(function ($, window, document) {

   'use strict';

   // Main function
   $.fn.scrollUp = function (options) {

       // Ensure that only one scrollUp exists
       if (!$.data(document.body, 'scrollUp')) {
           $.data(document.body, 'scrollUp', true);
           $.fn.scrollUp.init(options);
       }
   };

   // Init
   $.fn.scrollUp.init = function (options) {

       // Define vars
       var o = $.fn.scrollUp.settings = $.extend({}, $.fn.scrollUp.defaults, options),
           triggerVisible = false,
           animIn, animOut, animSpeed, scrollDis, scrollEvent, scrollTarget, $self;

       // Create element
       if (o.scrollTrigger) {
           $self = $(o.scrollTrigger);
       } else {
           $self = $('<a/>', {
               id: o.scrollName,
               href: '#top'
           });
       }

       // Set scrollTitle if there is one
       if (o.scrollTitle) {
           $self.attr('title', o.scrollTitle);
       }

       $self.appendTo('body');

       // If not using an image display text
       if (!(o.scrollImg || o.scrollTrigger)) {
           $self.html(o.scrollText);
       }

       // Minimum CSS to make the magic happen
       $self.css({
           display: 'none',
           position: 'fixed',
           zIndex: o.zIndex
       });

       // Active point overlay
       if (o.activeOverlay) {
           $('<div/>', {
               id: o.scrollName + '-active'
           }).css({
               position: 'absolute',
               'top': o.scrollDistance + 'px',
               width: '100%',
               borderTop: '1px dotted' + o.activeOverlay,
               zIndex: o.zIndex
           }).appendTo('body');
       }

       // Switch animation type
       switch (o.animation) {
           case 'fade':
               animIn = 'fadeIn';
               animOut = 'fadeOut';
               animSpeed = o.animationSpeed;
               break;

           case 'slide':
               animIn = 'slideDown';
               animOut = 'slideUp';
               animSpeed = o.animationSpeed;
               break;

           default:
               animIn = 'show';
               animOut = 'hide';
               animSpeed = 0;
       }

       // If from top or bottom
       if (o.scrollFrom === 'top') {
           scrollDis = o.scrollDistance;
       } else {
           scrollDis = $(document).height() - $(window).height() - o.scrollDistance;
       }

       // Scroll function
       scrollEvent = $(window).scroll(function () {
           if ($(window).scrollTop() > scrollDis) {
               if (!triggerVisible) {
                   $self[animIn](animSpeed);
                   triggerVisible = true;
               }
           } else {
               if (triggerVisible) {
                   $self[animOut](animSpeed);
                   triggerVisible = false;
               }
           }
       });

       if (o.scrollTarget) {
           if (typeof o.scrollTarget === 'number') {
               scrollTarget = o.scrollTarget;
           } else if (typeof o.scrollTarget === 'string') {
               scrollTarget = Math.floor($(o.scrollTarget).offset().top);
           }
       } else {
           scrollTarget = 0;
       }

       // To the top
       $self.click(function (e) {
           e.preventDefault();

           $('html, body').animate({
               scrollTop: scrollTarget
           }, o.scrollSpeed, o.easingType);
       });
   };

   // Defaults
   $.fn.scrollUp.defaults = {
       scrollName: 'scrollUp',      // Element ID
       scrollDistance: 300,         // Distance from top/bottom before showing element (px)
       scrollFrom: 'top',           // 'top' or 'bottom'
       scrollSpeed: 300,            // Speed back to top (ms)
       easingType: 'linear',        // Scroll to top easing (see http://easings.net/)
       animation: 'fade',           // Fade, slide, none
       animationSpeed: 200,         // Animation in speed (ms)
       scrollTrigger: false,        // Set a custom triggering element. Can be an HTML string or jQuery object
       scrollTarget: false,         // Set a custom target element for scrolling to. Can be element or number
       scrollText: 'Scroll to top', // Text for element, can contain HTML
       scrollTitle: false,          // Set a custom <a> title if required. Defaults to scrollText
       scrollImg: false,            // Set true to use image
       activeOverlay: false,        // Set CSS color to display scrollUp active point, e.g '#00FFFF'
       zIndex: 2147483647           // Z-Index for the overlay
   };

   // Destroy scrollUp plugin and clean all modifications to the DOM
   $.fn.scrollUp.destroy = function (scrollEvent) {
       $.removeData(document.body, 'scrollUp');
       $('#' + $.fn.scrollUp.settings.scrollName).remove();
       $('#' + $.fn.scrollUp.settings.scrollName + '-active').remove();

       // If 1.7 or above use the new .off()
       if ($.fn.jquery.split('.')[1] >= 7) {
           $(window).off('scroll', scrollEvent);

       // Else use the old .unbind()
       } else {
           $(window).unbind('scroll', scrollEvent);
       }
   };

   $.scrollUp = $.fn.scrollUp;

})(jQuery, window, document);