<script type="text/javascript">

/*var jWindow = $(window);

//滚动事件

jWindow.scroll(function(){

//窗口滚动的高度

var scrollHeight = jWindow.scrollTop();

//屏幕可减去

var screenHeight = jWindow.height();

//左侧滚动栏的高度

var sideHeight = $('#side').height();

if(scrollHeight + screenHeight > sideHeight){//滚动的高度加上屏幕的高度大于左侧栏的高度

$('#side').css({

'position':'fixed',

'top':-(sideHeight-screenHeight)+1,

'right':0

});

}else{

$('#side').css({

'position':'static',

});

}

});

window.onload = function(){

jWindow.trigger('scroll');

};

jWindow.resize(function(){

jWindow.trigger('scroll');//jquery方法

});*/

//返回的动引用

var $  = function(id){

return document.getElementById(id);

}

//一个元素绑定多个函数

var addEvent = function (obj,event,fn){

if(obj.addEventListener){

obj.addEventListener(event,fn,false);//冒泡或捕获的方式

}else if(obj.attachEvent){

obj.attachEvent('on'+event,fn);//ie 接受的事件模型

}

}

var domSider = $('side');

var scrollEvent  = function(){

var sideHeight = domSider.offsetHeight; //offsetHeight直接获取侧栏的高度

var screenHeight  = document.documentElement.clientHeight || document.body.clientHeight;

var scrollHeight = document.documentElement.scrollTop || document.body.scrollTop;

if(screenHeight+scrollHeight > sideHeight){

domSider.style.cssText = 'position:fixed;right:0px;top:'+(-(sideHeight-screenHeight))+'px';

}else{

domSider.style.position = 'static';

}

}

addEvent(window,'scroll',function(){

scrollEvent();

});

addEvent(window,'resize',function(){

scrollEvent();

});

滚动后：：：：

滚动前：：：

</script>