JS 获取网页内容高度 和 网页可视高度 支持IE6789 Firefox Chrome

function getClientHeight()
 {
     //可见高
     var clientHeight=document.body.clientHeight;//其它浏览器默认值
     if(navigator.userAgent.indexOf("MSIE 6.0")!=-1)
     {
         clientHeight=document.body.clientHeight;
     }
     else if(navigator.userAgent.indexOf("MSIE")!=-1)
     {
         //IE7 IE8
         clientHeight=document.documentElement.offsetHeight
     }
 
     if(navigator.userAgent.indexOf("Chrome")!=-1)
     {
         clientHeight=document.body.scrollHeight;
     }
 
     if(navigator.userAgent.indexOf("Firefox")!=-1)
     {
         clientHeight=document.documentElement.scrollHeight;
     }
     return clientHeight;
 }
 
 //获得网页内容高度
 function getContentHeight()
 {
     //可见高
     var ContentHeight=document.body.scrollHeight;//其它浏览器默认值
 
     if(navigator.userAgent.indexOf("Chrome")!=-1)
     {
         ContentHeight= document.body.clientHeight;
     }
 
     if(navigator.userAgent.indexOf("Firefox")!=-1)
     {
         ContentHeight=document.body.offsetHeight;
     }
     return ContentHeight;
 }