Using Javascript form validation in WordPress - Firefox issues

Question

I have been struggling for a while to get javascript to validate a WordPress based HTML form which uses radio buttons. I finally came up with a solution with was a bit long-winded but worked - at least in IE and Chrome - however, it doesn't work in Firefox (which suggests my code is a bit sloppy). I think my radio button reference is the issue. Can anyone help with what I have done wrong - apart from use an inefficient approach for validation :-)?
A simplified version of my form:
<script>
function validateForm()
var aa=document.forms["personalise"]["motivation"]["1a"];
var ab=document.forms["personalise"]["motivation"]["1b"];
var ac=document.forms["personalise"]["motivation"]["1c"];
var ad=document.forms["personalise"]["motivation"]["1d"];
var ae=document.forms["personalise"]["motivation"]["1e"];
if (!(aa.checked == true || ab.checked == true || ac.checked == true || ad.checked == true || ae.checked == true))
alert("Question 1 must be completed");
return false;
</script>
<form name="personalise" action="insertdatatest.php" onsubmit="return validateForm()" method="post">
1. Are you seriously planning to quit </b>:&nbsp;&nbsp;
<input id="1a" type="Radio" title="" name="motivation" value="1" /> Within the next 2 weeks
<input id="1b" type="Radio" title="" name="motivation" value="2" /> Within the next 30 days
<input id="1c" type="Radio" title="" name="motivation" value="3" /> Within the next 3 months
<input id="1d" type="Radio" title="" name="motivation" value="4" /> No, I am not currently planning to quit
<input id="1e" type="Radio" title="" name="motivation" value="5" /> I have already quit
<input type="submit" value = "Submit">
</form>
For My Website : http://www.schoolanduniversity.com

Answer 1

Thanks for your support,
This will partly solve the issue I think. Now, the validation is indeed only done for the first form. But I need to save data twice when entering data in the second grid. When checking the error console in mozilla I see following error:
Error: grid[r] is undefined
Which is reffering to:
          if ((grid[r] [1] != missing) ||(grid[r][2] != missing) || (grid[r][3] != missing))
When I save again, the data will be saved without this error.
Is there a way to exclude the second grid in the if Statement?
Regards,
Erik