上下弹动的导航条

特效说明：

把下列代码加到网页的<Body></Body>标签之间

要完成此效果把如下代码加入到<body>区域中

var YY=0;  
var ch=0;
var oh=0;
var yon=0;

var ns4=document.layers?1:0
var ie=document.all?1:0
var ns6=document.getElementById&&!document.all?1:0

if(ie){
YY=document.body.clientHeight;
point1.style.top=YY;
}
else if (ns4){
YY=window.innerHeight;
document.point1.pageY=YY;
document.point1.visibility="hidden";
}
else if (ns6){
YY=window.innerHeight
document.getElementById('point1').style.top=YY
}

function reloc1()
{

if(yon==0){YY=YY-xstep;}
else{YY=YY+xstep;}
if (ie){
ch=document.body.clientHeight;
oh=point1.offsetHeight;
}
else if (ns4){
ch=window.innerHeight;
oh=document.point1.clip.height;
}
else if (ns6){
ch=window.innerHeight
oh=document.getElementById("point1").offsetHeight
}
        
if(YY<0){yon=1;YY=0;}
if(YY>=(ch-oh)){yon=0;YY=(ch-oh);}
if(ie){
point1.style.left=XX;
point1.style.top=YY+document.body.scrollTop;
}
else if (ns4){
document.point1.pageX=XX;
document.point1.pageY=YY+window.pageYOffset;
}
else if (ns6){
document.getElementById("point1").style.left=XX
document.getElementById("point1").style.top=YY+window.pageYOffset
}

}

function onad()
{
if(ns4)
document.point1.visibility="visible";
loopfunc();
}
function loopfunc()
{
reloc1();
setTimeout('loopfunc()',delay_time);
}

if (ie||ns4||ns6)
window.onload=onad
</script>