var CSS = {            getStyle:function(elem,name){//获取样式                if(elem.style[name]){                     return elem.style[name];                 } else if(elem.currentStyle){                     return elem.currentStyle[name];                 } else if(document.defaultView && document.defaultView.getComputedStyle){                     name = name.replace(/([A-Z])/g,"-$1");                     name = name.toLowerCase();                     var s = document.defaultView.getComputedStyle(elem,"");                     return s && s.getPropertyValue(name);                 } else{                     return null;                 }             },            getPageX:function(elem){//元素相对于整个文档的X位置                return elem.offsetParent? elem.offsetLeft + CSS.getPageX(elem.offsetParent) : elem.offsetLeft;            },            getPageY:function(elem){//元素相对于整个文档的Y位置                return elem.offsetParent? elem.offsetTop + CSS.getPageY(elem.offsetParent) : elem.offsetTop;            },            getParentX:function(elem){//元素相对于父亲的X位置                return elem.parentNode === elem.offsetParent ? elem.offsetLeft : CSS.getPageX(elem) - CSS.getPageX(elem.parentNode);            },            getParentY:function(elem){//元素相对于父亲的Y位置                return elem.parentNode === elem.offsetParent ? elem.offsetTop : CSS.getPageY(elem) - CSS.getPageY(elem.parentNode);            },            getPosX:function(elem){//元素相对于它的CSS容器的X位置                 return parseInt(CSS.getStyle(elem,"left"));             },            getPosY:function(elem){//元素相对于它的CSS容器的Y位置                 return parseInt(CSS.getStyle(elem,"top"));             },            setOpacity:function(elem,level){                if(elem.filters){                     elem.style.filters = ‘alpha(opacity=‘+level+‘)‘;                 }else{                     elem.style.opacity = level/100;                 }                             }        };