用js实现控制内容的向上向下滚动效果

<SCRIPTlanguage=JavaScript1.2>
iens6=document.alldocument.getElementById

//specifyspeedofscroll(greater=faster)
varspeed=10

if(iens6){
document.write(<divid=containerstyle=position:relative;width:600;height:430;border:0pxsolidblack;overflow:hidden>)
document.write(<divid=contentstyle=position:absolute;width:590;left:0;top:0>)
}
</SCRIPT>
<SCRIPTlanguage=JavaScript1.2>
if(iens6)
document.write(</div></div>)
</SCRIPT>
<SCRIPTlanguage=JavaScript1.2>
if(iens6){
varcontentheight=crossobj.offsetHeight
}
elseif(ns4){
varcrossobj=document.nscontainer.document.nscontent
varcontentheight=crossobj.clip.height
}

functionmovedown(){
crossobj.style.top=parseInt(crossobj.style.top)-speed
elseif(ns4&&crossobj.top>=(contentheight*(-1)+100))
crossobj.top-=speed
movedownvar=setTimeout(movedown(),100)
}

functionmoveup(){
if(iens6&&parseInt(crossobj.style.top)<=0)
crossobj.style.top=parseInt(crossobj.style.top)+speed
elseif(ns4&&crossobj.top<=0)
crossobj.top+=speed
moveupvar=setTimeout(moveup(),100)

}

functiongetcontent_height(){
if(iens6)
contentheight=crossobj.offsetHeight
elseif(ns4)
document.nscontainer.document.nscontent.visibility=show
}
window.onload=getcontent_height
</SCRIPT>