Problem in zip code validation

[nicknick]

Hello! There is something wrong in the code below. What is it? Can you help me please? The form validation was working just fine when I added the last 'if' for zip code validation. The function didn't work and returned true. The code is:

<script type="text/javascript">
function validateForm()
{
var y=document.forms["form"]["firstname"].value;
var f=document.forms["form"]["zipcode"].value;
var x=document.forms["form"]["email"].value;
var atpos=x.indexOf("@");
var dotpos=x.lastIndexOf(".");
if (y==null || y=="NAME")
  {
  alert("First name must be filled out");
  return false;
  }
if (atpos<1 || dotpos<atpos+2 || dotpos+2>=x.length)
  {
  alert("Not a valid e-mail address");
  return false;
  }
}
var re='/(^\d{5}$)/';
if (f!=re)
  { 
  alert ("Not a valid address");
  return false;
  }
}
</script>

Any ideas or advice? Thank you in advance!

[Philip M]

if (!/\d{5}/.test(f)) {
alert ("Invalid zip code");
// erase the field with wrong info in it
// and refocus on it
return false;
}

You may wish to use
if (/^\d{5}\-?\d{4}$/gi.test(f)) { // 5 digits, optional hyphen, 4 digits
as I understand some US zip codes are in the form 12345-6789


Quizmaster: In 1918 the Czechs and the Slovaks united to form which country?
Contestant: Prussia

[nicknick]

Thank you very much Philip! Now it is working! Thank you again!