关于表格触发onclick事件的问题

Question

<table id=m onclick="a()">
<tr><td>affff</td></tr>
<tr>
<td>adfgdfgdfg</td></tr>
<tr>
<td>adfgdfgdfgfd</td></tr>
</table><script>
function a()
{
o=event.srcElement
if(o.tagName!="TD") return
alert(o.innerText)
}
</script>

Answer 1

<table id=m onclick="a()" border>
<tr><td>affff</td></tr>
<tr>
<td>adfgdfgdfg</td></tr>
<tr>
<td>adfgdfgdfgfd</td></tr><tr><td>affff</td></tr>
<tr>
<td>adfgdfgdfg</td></tr>
<tr>
<td>adfgdfgdfgfd</td></tr>
</table><script>
function a()
{
o=event.srcElement
if(o.tagName!="TD") return
o.bgColor="red"
}
</script>