<table >
<tr><td>Header</td></tr>
<tr><td><input type=checkbox name=aaaa onclick="alert(this.parentElement.parentElement.rowIndex-1);"></td></tr>
<tr><td><input type=checkbox name=aaaa onclick="alert(this.parentElement.parentElement.rowIndex-1);"></td></tr>
</table>
<tr><td>Header</td></tr>
<tr><td><input type=checkbox name=aaaa onclick="alert(this.parentElement.parentElement.rowIndex-1);"></td></tr>
<tr><td><input type=checkbox name=aaaa onclick="alert(this.parentElement.parentElement.rowIndex-1);"></td></tr>
</table>
{
var a = document.getElementsByName(e.name);
for(var i=0; i<a.length; i++)
{
if(a[i]==e){alert("下标 = "+ i); break;}
}
}