checkbox - test plain for mutt

<table width="100%">
<tr class=tablelist_tr>
<td align="center" class=tt><input value="全选" type="button" onclick="setAll()"></td>
<td align="center" class=tt><input value="清除" type="button" onclick="clsAll()"><br></td>
</tr>
<tr class=tablelist_tr>
<td align="center" class=tt><input id="g11" type="checkbox">g11<br></td>
<td align="center" class=tt><input id="g12" type="checkbox">g12<br><br></td>
</tr>
<tr class=tablelist_tr>
<td align="center" class=tt><input id="g21" type="checkbox">g21<br></td>
<td align="center" class=tt><input id="g22" type="checkbox">g22<br><br></td>
</tr>
<tr class=tablelist_tr>
<td align="center" class=tt><input id="g31" type="checkbox">g31<br></td>
<td align="center" class=tt><input id="g32" type="checkbox">g32<br><br></td>
</tr>
<tr class=tablelist_tr>
<td align="center" class=tt><input value="全选" type="button" onclick="setAll()"></td>
<td align="center" class=tt><input value="清除" type="button" onclick="clsAll()"><br></td>
</tr>
</table>
<br>

<script>
function setAll() {
var cs = document.getElementsByTagName("input");
for(var i = 0; i < cs.length; i++) {
if(cs[i].type == "checkbox") {
cs[i].checked=true;
}
}
}
function clsAll() {
var cs = document.getElementsByTagName("input");
for(var i = 0; i < cs.length; i++) {
if(cs[i].type == "checkbox") {
cs[i].checked=false;
}
}
}
</script>