点击隐藏页面左栏或右栏实现js代码

点击隐藏页面左栏或右栏(同一TABLE中)

<style type="text/css"> 
<!-- 
.navPoint {COLOR: white; CURSOR: hand; FONT-FAMILY: Webdings; FONT-SIZE: 9pt} 
.STYLE1 {FONT-FAMILY: Webdings; FONT-SIZE: 9pt; cursor: hand;} 
--> 
</style> 
<script> 
function switchSysBar(){ 
if (switchPoint.innerText==3){ 
switchPoint.innerText=4 
document.all("frmTitle").style.display="none" 
}else{ 
switchPoint.innerText=3 
document.all("frmTitle").style.display="" 
}} 
</script> 
<table border="0" cellPadding="0" cellSpacing="0" height="100%" width="100%"> 
<tr> 
<td width="20%" align="middle" vAlign="center" noWrap bgcolor="#CC99FF" id="frmTitle" name="frmTitle"> </td> 
<td class=a2 style="WIDTH: 9pt"><table border="0" cellPadding="0" cellSpacing="0" height="100%"> 
<tr> 
<td style="HEIGHT: 100%" onClick="switchSysBar()"><font style="FONT-SIZE: 9pt; CURSOR: default; COLOR: #ffffff"> <br/> 
<br/> 
<br/> 
<br/> 
<br/> 
<br/> 
<br/> 
<br/> 
<font color="#FF0000"><br/> 
<br/> 
<br/> 
<br/> 
<br/> 
<span class="STYLE1" id="switchPoint" title="关闭/打开左栏">3</span><br/> 
<br/> 
<br/> 
<br/> 
<br/> 
<br/> 
</font><br/> 
<br/> 
屏幕切换 </font></td> 
</tr> 
</table></td> 
<td bgcolor="#FFCC99" style="WIDTH: 100%"> </td> 
</tr> 
</table> 
想把隐藏左右栏的那个按钮按成图片，改一下JS，IMG增加ID，这里id=aa，也可以换成其它的名称，参考如下： 
<script> 
function switchSysBar(){ 
if (document.all.aa.src.indexOf("bl_1")!=-1){ 
aa.src="images/al_1.gif" 
document.all("frmTitle").style.display="none" 
}else{ 
aa.src="images/bl_1.gif" 
document.all("frmTitle").style.display="" 
} 
} 
</script> 
<table width="100%" height="100%" border="0" cellspacing="0" cellpadding="0"> 
<tr> 
<td width="770" valign="top"> </td> 
<td width="10" onClick="switchSysBar()"><img id="aa" src="images/bl_1.gif" title="关闭/打开功能导航"></td> 
<td width="191" valign="top" id="frmTitle" name="frmTitle"> </td> 
</tr> 
</table>