<script language="javascript" type="text/javascript">
// <!CDATA[

function img1_onclick(id) {
var imgName=document.getElementById(id).src.replace(/.*//([^//]+)/..+/,'$1');

if(imgName=="True")
{
document.getElementById(id).src="Images/False.jpg";
}else
{
document.getElementById(id).src="Images/True.jpg";
}
}

// ]]>
</script>

<img id="img1" src="Images/False.jpg" runat="server" onclick="return img1_onclick('img1')" />s

replace(/.*//([^//]+)/..+/,'$1')取得圖片名