[求助]怎么在网页中实现（全选）（反选）（连续播放）功能

[CODE]
<script language="javascript">
function checkall()
{
for (var i = 0;i<form.che.length;i++)
{
var e = form.che[i];
if(e.name != 'cheall')
{
e.checked = form.cheall.checked;
}
}
}
function checkall_n()
{
for (var i = 0;i<form.che.length;i++)
{
var e = form.che[i];
if(e.checked==true)
{
e.checked = false;
}
else
{
e.checked = true;
}
}
}
</script>

<form id="form" name="form" method="post" action="">
<input name="che" type="checkbox" id="che" value="checkbox" />
a
<input name="che" type="checkbox" id="che" value="checkbox" />
b
<input name="che" type="checkbox" id="che" value="checkbox" />
c
<input name="che" type="checkbox" id="che" value="checkbox" />
d
<input name="che" type="checkbox" id="che" value="checkbox" />
e<br>
<input name="cheall" type="checkbox" id="cheall" value="checkbox" onclick="checkall()"/>
全选&nbsp;&nbsp;
<span onclick="checkall_n()" style="cursor:hand;">点击反选</span>
</form>[/CODE]