/********************
*獲取窗口滾動條高度
******************/
function getScrollTop()
{
var scrollTop=0;
if(document.documentElement&&document.documentElement.scrollTop)
{
    scrollTop=document.documentElement.scrollTop;
}
else if(document.body)
{
    scrollTop=document.body.scrollTop;
}
return scrollTop;
}
 

/********************
* 獲取窗口可視範圍的高度
*******************/
function getClientHeight()
{
var clientHeight=0;
if(document.body.clientHeight&&document.documentElement.clientHeight)
{
    var clientHeight = (document.body.clientHeight<document.documentElement.clientHeight)?document.body.clientHeight:document.documentElement.clientHeight;
}
else
{
    var clientHeight = (document.body.clientHeight>document.documentElement.clientHeight)?document.body.clientHeight:document.documentElement.clientHeight;
}
return clientHeight;
}
 

/********************
* 獲取文檔內容實際高度
*******************/
function getScrollHeight()
{
return Math.max(document.body.scrollHeight,document.documentElement.scrollHeight);
}