<script language="javascript">
function selectIt(){
form=document.lzyy
action=event.srcElement.name
for(var i=0 ;i<form.elements.length;i++){
if(form.elements[i].name=="checkbox"){
e=form.elements[i]
e.checked=(action=="selectAll")?(form.selectAll.checked):(!e.checked)
}
}
}
</script>
<form name="lzyy">
<p> 全 选
<input type="checkbox" name="selectAll" value="checkbox" onClick="selectIt()">
<br>
反 选
<input type="checkbox" name="invest" value="checkbox" onClick="selectIt()">
<br>
Item1
<input type="checkbox" name="checkbox" value="checkbox">
<br>
Item2
<input type="checkbox" name="checkbox" value="checkbox">
<br>
Item3
<input type="checkbox" name="checkbox" value="checkbox">
<br>
Item4
<input type="checkbox" name="checkbox" value="checkbox">
<br>
Item5
<input type="checkbox" name="checkbox" value="checkbox">
</p>
</form>