用js实现控制内容的向上向下滚动效果

  <SCRIPT language=JavaScript1.2>

  iens6=document.all||document.getElementById

  ns4=document.layers

  //specify speed of scroll (greater=faster)

  var speed=10

  if (iens6){

  document.write('<div id="container" style="position:relative;width:600;height:430;border:0px solid black;overflow:hidden">')

  document.write('<div id="content" style="position:absolute;width:590;left:0;top:0">')

  }

  </SCRIPT>

  <SCRIPT language=JavaScript1.2>

  if (iens6)

  document.write('</div></div>')

  </SCRIPT>

  <SCRIPT language=JavaScript1.2>

  if (iens6){

  var crossobj=document.getElementById? document.getElementById("content") : document.all.content

  var contentheight=crossobj.offsetHeight

  }

  else if (ns4){

  var crossobj=document.nscontainer.document.nscontent

  var contentheight=crossobj.clip.height

  }

  function movedown(){

  if (iens6&&parseInt(crossobj.style.top)>=(contentheight*(-1)+100))

  crossobj.style.top=parseInt(crossobj.style.top)-speed

  else if (ns4&&crossobj.top>=(contentheight*(-1)+100))

  crossobj.top-=speed

  movedownvar=setTimeout("movedown()",100)

  }

  function moveup(){

  if (iens6&&parseInt(crossobj.style.top)<=0)

  crossobj.style.top=parseInt(crossobj.style.top)+speed

  else if (ns4&&crossobj.top<=0)

  crossobj.top+=speed

  moveupvar=setTimeout("moveup()",100)

  }

  function getcontent_height(){

  if (iens6)

  contentheight=crossobj.offsetHeight

  else if (ns4)

  document.nscontainer.document.nscontent.visibility="show"

  }

  window.onload=getcontent_height

  </SCRIPT>