判断滚动条是否已到顶部！

Question

TRY:
<div id="test" style="width:300;height:300;overflow-y:scroll;" onscroll="if(this.scrollTop==0){alert('top');}">
<table width="100%" height="600">
<tr>
<td>t<p>e<p>s<p>t</td>
</tr>
</table>
</div>

Answer 1

程序是这样的：
CRIPT LANGUAGE=javascript>
<!--
// JavaScript Document
var Xpos = 0;
var Ypos = 0;
var Ygravity = 0.9;
var scrollPos = 0;
var oldScrollPos = 0;
function FloatMenu() 
{
docWidth =668; // update document width
oldScrollPos = scrollPos;
scrollPos = document.body.scrollTop; // update scrollbar position
Xpos = docWidth;
Yboundary = scrollPos + 20;
if(document.body.scrollTop>230)
{
if (document.getElementById("floater").offsetTop < Yboundary - 10) // Object is behind boundary
Ypos += 2;
if (document.getElementById("floater").offsetTop > Yboundary + 10) // Object is past boundary
Ypos -= 2;
Ypos *= Ygravity; // Slow object down
floater.style.pixelLeft = Xpos + 90;
floater.style.pixelTop += Ypos; // Make object bounce
//在此添加判断滚动条是否到顶部
if(......&&floater.style.pixelTop>=230)
{
  floater.style.pixelTop -= Ypos; // Make object bounce
}
}
}
window.setInterval("FloatMenu()", 20);
//-->
</SCRIPT>
<div id="floater" style="position: absolute; left: 760px; top: 230px;">
   <OBJECT id=ShockwaveFlash2   codebase="http://download.macromedia.com/pub/shockwave/cabs/flash/swflash.cab#version=6,0,29,0" 
   height=490 width=221 classid=clsid:D27CDB6E-AE6D-11cf-96B8-444553540000>
   <PARAM NAME="_cx" VALUE="5847"><PARAM NAME="_cy" VALUE="14711"><PARAM NAME="FlashVars" VALUE="">
   <PARAM NAME="Movie" VALUE="flash/quickmenu.swf"><PARAM NAME="Src" VALUE="flash/quickmenu.swf">
   <PARAM NAME="WMode" VALUE="Transparent"><PARAM NAME="Play" VALUE="-1"><PARAM NAME="Loop" VALUE="-1">
   <PARAM NAME="Quality" VALUE="High"><PARAM NAME="SAlign" VALUE=""><PARAM NAME="Menu" VALUE="-1">
   <PARAM NAME="Base" VALUE=""><PARAM NAME="AllowScriptAccess" VALUE="always"><PARAM NAME="Scale" VALUE="ShowAll">
   <PARAM NAME="DeviceFont" VALUE="0"><PARAM NAME="EmbedMovie" VALUE="0"><PARAM NAME="BGColor" VALUE="">
   <PARAM NAME="SWRemote" VALUE=""><PARAM NAME="MovieData" VALUE=""><PARAM NAME="SeamlessTabbing" VALUE="1">
  <embed src="flash/quickmenu.swf" width="221" height="490" quality="high" pluginspage="http://www.macromedia.com/go/getflashplayer" type="application/x-shockwave-flash" wmode="transparent"></embed> </OBJECT>
</div>

Answer 2

if(......&&floater.style.pixelTop>=230)
{
  floater.style.pixelTop -= Ypos; // Make object bounce
}
这段怎么写?

Answer 3

if((document.getElementById("floater").scrollTop==0)&&(floater.style.pixelTop>=230))

Answer 4

用获取document.body.scrollTop的值来判断