upPanelScroll

uppanel.js

(function($){

				$.fn.upPanel = function(options) {
					
					var 

						settings = $.extend({
							fade : false, // int, etc;
							speed : 300, // up scroll speed
							waterline : 600, // 'auto', 'formula'
							leftPosition : false, // { nearElement: 'selector', space: 10 }
							onShow : $.noop,
							onHide : $.noop
						}, options),

						$panel = $(this),

						methods = {

							init : function() {
								// base css for panel
								$panel.hide().css({position: 'fixed'})
								// smart waterline
								if (typeof settings.waterline == 'string' && /auto/.test()) {
									methods.helpers.waterLine.formula = $.trim('auto 1/3'.replace('auto', ''));
									methods.helpers.waterLine.isCalc = true;
									methods.helpers.waterLine.value = methods.helpers.waterLine.calculate();
								}
							},

							scrollHandler : function() {

								if ( $(window).scrollTop() > settings.waterLine ) {

				        			if ( ! $panel.is('visible') ) {
				        				
				        				methods.helpers.panelToggle('show')
				        				
				        				if ( settings.leftPosition !== false ) {
				        					methods.helpers.calculateLeft();
				        				}

				        			}

				        		} else {
				        			methods.helpers.panelToggle('hide')
				        		}

							},

							resizeHandler : function() {
								if ( settings.leftPosition !== false ) {
		        					methods.helpers.calculateLeft();
		        				}
							},

							upstairHandler : function() {
								var mode = window.opera ? 'html' : 'html, body';
								$(mode).animate({scrollTop: 0}, settings.speed, settings.onComplete)
							},

							helpers : {

								panelToggle : function(mode) {
									var mthd = mode == 'show' ? 'fadeIn' : 'fadeOut',
										clbck = mode == 'show' ? 'onShow' : 'onHide';
									$panel[mthd]( (!settings.fade ? 1 : settings.fade) , function() { settings[clbck].call($panel) } )
								},

								calculateLeft : function() {
										
									var b = $(settings.leftPosition.near).offset().left - settings.leftPosition.margin,
			        					w = $panel.outerWidth();
			        				$panel.css({left: (b - w)})

								},

								waterLine : {

									formula : '',

									value : 0,

									isCalc : false,

									calculate : function() {

									}

								}

							}

						};

					methods.init();

					$(window)
						.scroll(methods.scrollHandler)
						.resize(methods.resizeHandler);

					$panel
						.on('click', methods.upstairHandler)

					return this;

				}
	        	
			})(jQuery)