ayuda con checkbox....

[Saruman]

Código HTML:

<script language="javascript">
 function selecciona() {
  var d = document.all;
  var total_check = d.check_name.length;
  if (total_check != null) {
   for (i=0; i<total_check; i++) {
	if (d.check_name[i].checked == false) {
	 d.check_name[i].checked = true;
	} else {
	 d.check_name[i].checked = false;
	}
   }
  } else {
   if (d.check_name.checked == false) {
	d.check_name.checked = true;
   } else {
	d.check_name.checked = false;
   }
  }
 }
</script>