jQuery图片滚动图片的效果(另类实现)

(function( $ ){
     var slider = function( elem , args ){
         this.config = $.extend({
             effect   : 'x', //效果  水平 - x
             speed    : 600 , //动画速度
             trigger  : 'mouseenter', //触发事件
             callback : null , // 回调函数
             view     : 7
         }, args || {}  );

         this.history = [];//记录移动的历史记录
         this.index = 0;
         this.el = elem;
         this.length = this.el.find('li').length;//记录总长度
         this.width = this.el.find('li').eq(0).outerWidth();//记录每一个单项的宽度
         this.init();
     }
     slider.prototype = {
         constructor : slider,
         init : function(){
             this.bindEvents();
         },
         bindEvents : function(){
             this.prev();
             this.next();
         },
         prev :  function(){
             this.el.find('[data-type="left"]').click( $.proxy(function(){

                 if( !this.history.length ) return;//如果记录为空，证明没有进行移动过,所以直接return

                 this.index--;
                 var step = this.history.pop();//取最后的移动步骤
                 var move =  step * this.width;//算出移动宽度
                 this.el.find("ul").animate( { "left" : "+="+move+"px" } , this.config.speed )

             } , this));
         },
         next : function(){
             this.el.find('[data-type="right"]').click( $.proxy(function(){
                 //如果是当前的最后一页,直接return
                 if(this.index == parseInt( this.length / this.config.view , 10 ) ){
                     return;
                 }
                 this.index++;
                 //这个计算很重要
                 //计算 ( 下一页 * view ) 展示个数是否大于总长度 : 好比当前在第一页 (1+1) *7 > 12(总长度)
                 //则this.step 赋值为取余 ,也就是剩下要移动的个数
                 if( this.config.view * (this.index+1) > this.length ){
                     this.step =  this.length%this.config.view;
                 }else{
                     //否则移动展示的个数
                     this.step = this.config.view;
                 }
                 //记录移动的历史记录
                 this.history.push(this.step);
                 var move = -1 * this.step * this.width;
                 this.el.find("ul").animate( { "left" : "+="+move+"px" } , this.config.speed )

             } , this));
         }
     }

     $.fn.slider = function( args ){
         return this.each(function(){
             var el = this;
             var plugins = new slider( $( el ) , args );
             $(el).data("slider" , plugins );
         });
     }
 })(jQuery)