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Forms >>> Validation Zip Code.

Ensure that your visitors enter a properly formatted 5 digit, or 5 digit+4 zip code. The visitor is alerted if any information is invalid and asked to try again.


Add the below code to the <body> section of your page:

<script language="javascript" type="text/javascript">
/* Visit for full source code
and get more free JavaScript, CSS and DHTML scripts! */
<!-- Begin
function validateZIP(field) {
var valid = "0123456789-";
var hyphencount = 0;

if (field.length!=5 && field.length!=10) {
alert("Please enter your 5 digit or 5 digit+4 zip code.");
return false;
for (var i=0; i < field.length; i++) {
temp = "" + field.substring(i, i+1);
if (temp == "-") hyphencount++;
if (valid.indexOf(temp) == "-1") {
alert("Invalid characters in your zip code.  Please try again.");
return false;
if ((hyphencount > 1) || ((field.length==10) && ""+field.charAt(5)!="-")) {
alert("The hyphen character should be used with a properly formatted 5 digit+four zip code, like '12345-6789'.   Please try again.");
return false;
return true;
//  End -->
<form name=zip onSubmit="return validateZIP(">
Zip: <input type=text size=30 name=zip>
type=submit value="Submit">

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