俺没有分了，不过这个问题是很有意思的

Question

<script>
function mm(){
var obj = event.srcElement;
while(obj = obj.offsetParent){
if(obj.tagName=="TABLE") break;
}
alert(obj.tagName);
}
</script>
<table id="tb1" border=1 cellspacing=0 width=214 onclick="mm()" bordercolor="#000000" style="border-collapse: collapse" cellpadding="0" height="129">
<tr><td width="37" height="16">11</td><td width="37" height="16">12</td>
  <td width="6" height="16">13</td><td width="82" height="16">14</td></tr>
</table><table id="tb1" border=1 cellspacing=0 width=214 onclick="mm()" bordercolor="#000000" style="border-collapse: collapse" cellpadding="0" height="129">
<tr><td width="37" height="16">11</td><td width="37" height="16">12</td>
  <td width="6" height="16">13</td><td width="82" height="16">14</td></tr>
</table>
<table id="tb1" border=1 cellspacing=0 width=214 onclick="mm()" bordercolor="#000000" style="border-collapse: collapse" cellpadding="0" height="129">
<tr><td width="37" height="16">11</td><td width="37" height="16">12</td>
  <td width="6" height="16">13</td><td width="82" height="16">14</td></tr>
</table>
<table id="tb1" border=1 cellspacing=0 width=214 onclick="mm()" bordercolor="#000000" style="border-collapse: collapse" cellpadding="0" height="129">
<tr><td width="37" height="16">11</td><td width="37" height="16">12</td>
  <td width="6" height="16">13</td><td width="82" height="16">14</td></tr>
</table>

Answer 1

加个循环判断是哪个表格<script>
function mm(){
var obj = event.srcElement;
while(obj = obj.offsetParent){
if(obj.tagName=="TABLE") break;
}
for(i=0;i<document.all.tags("TABLE").length;i++){
if(document.all.tags("TABLE")[i]==obj)
   alert("TABLE："+i);
}
}
</script>