/* Class: ScrollSpy Author: David Walsh Website: http://davidwalsh.name/js/scrollspy Version: 1.0.0 Date: 5/19/2009 Built For: MooTools 1.2.2 */ /* scroll spy plugin / class */ var ScrollSpy = new Class({ /* implements */ Implements: [Options,Events], /* options */ options: { min: 0, mode: 'vertical', max: 0, container: window, onEnter: $empty, onLeave: $empty, onTick: $empty }, /* initialization */ initialize: function(options) { /* set options */ this.setOptions(options); this.container = $(this.options.container); this.enters = this.leaves = 0; this.max = this.options.max; /* fix max */ if(this.max == 0) { var ss = this.container.getScrollSize(); this.max = this.options.mode == 'vertical' ? ss.y : ss.x; } /* make it happen */ this.addListener(); }, /* a method that does whatever you want */ addListener: function() { /* state trackers */ this.inside = false; this.container.addEvent('scroll',function() { /* if it has reached the level */ var position = this.container.getScroll(); var xy = this.options.mode == 'vertical' ? position.y : position.x; /* if we reach the minimum and are still below the max... */ if(xy >= this.options.min && xy <= this.max) { /* trigger Enter event if necessary */ if(!this.inside) { /* record as inside */ this.inside = true; this.enters++; /* fire enter event */ this.fireEvent('enter',[position,this.enters]); } /* trigger the "tick", always */ this.fireEvent('tick',[position,this.inside,this.enters,this.leaves]); } else { /* trigger leave */ if(this.inside) { this.inside = false; this.leaves++; this.fireEvent('leave',[position,this.leaves]); } } }.bind(this)); } });