help checkbox

I have 3 checkboxes

I need a javascript that will pop up a message or something if the end user tries to select boxes 1 and 3

2 and 3 is ok, 1 and 2 is ok, or just 1 2 or 3 is ok, but 1 and 3 is NOT ok..

ANY help would be greatly appriciated!

Thanks..

 

Using the following sample names for the form and checkboxes:

<form name="myform" id="myform" action="" method="post">
<input type="checkbox" name="chk[]" />
<input type="checkbox" name="chk[]" />
<input type="checkbox" name="chk[]" />
</form>

Code (markup):

<script type="text/javascript">
function mycheck ()
{
   var mycheckbox = document.myform.elements["chk[]"];
   if (mycheckbox[0].checked && mycheckbox[2].checked)
   {
      alert("Not OK");
      return false;
   }
   else
   {
      return true;
   }
}
</script>

Code (markup):

 

Thank alot! I will try this in the morning..

 

Worked great! just had to add the onChange="mycheck()" to the elements..

Thanks again..

 

thanks for this. Very useful