用JS脚本如何实现我要求的这种功能,高手帮帮忙!

<SCRIPT LANGUAGE="JavaScript">
<!--
document.write('<span style="position:relative;width:150px;height:20px;border:1px solid black;font:bold 12px Verdana;padding:2px" onClick="showhide(1);event.cancelBubble=1" ><span style="cursor:hand;width:100%">Script Categories <img src="tridown.gif"></span>')
document.write('<div id="innermenu" style="position:absolute;left:2;top:16;width:240px;height:150px;border:1px solid black;background-color:white;overflow-y:scroll;visibility:hidden;">')
document.write("<a href=dd>gaga</a>")
function showhide(state){
var cacheobj=document.getElementById("innermenu").style
if (state==0)
cacheobj.visibility="hidden"
else
cacheobj.visibility=cacheobj.visibility=="hidden"? "visible" : "hidden"
}
//-->
</SCRIPT><SCRIPT LANGUAGE="JavaScript">
<!--//-->
</SCRIPT>