<script>
//Check all radio/check buttons script- by Wsabstract.com
//Visit Website Abstraction (http://wsabstract.com) for script
//Credit must stay intact for use

// Erweitert Michael Raberger
// http://www.look4it.at 

function checkall(formname,checkname,thestate){
  var el_collection=eval("document.forms."+formname+"."+checkname)
  for (c=0;c<el_collection.length;c++)
  el_collection[c].checked=thestate
}

function check_(){ // Fkt. Michael Raberger
  var check = document.checkform.checkboxen.checked;
  if(check == true)  checkall('test','v1',true);
  if(check == false) checkall('test','v1',false);
}
</script>

<form name="test">
<input type="checkbox" name="v1"> Box 1<br>
<input type="checkbox" name="v1"> Box 2<br>
<input type="checkbox" name="v1"> Box 3<br>


</form>

<!-- Änderung Michael Raberger -->
Alle Auswählen <input type="Checkbox" name="checkall" value="v" onclick="javascript:checkall('test','v1',true)"><BR />
Alle Abwählen <input type="Checkbox" name="checkall" value="v" onclick="javascript:checkall('test','v1',false)"><BR /><BR />

<form name="checkform" action="" method="">
Alle Auswählen / Abwählen <input type="Checkbox" name="checkboxen" value="v" onclick="check_()">
</form>

<!-- checkall(name of form, common name of checkbox group, true or false)-->

<a href="javascript:checkall('test','v1',true)">alle auswählen</a><br>
<a href="javascript:checkall('test','v1',false)">keine auswählen</a>