ZIP Code (US Postal Code) validation

Question

Javascript Regex Literal:

US Zip Codes: /(^\d{5}$)|(^\d{5}-\d{4}$)/

var isValidZip = /(^\d{5}$)|(^\d{5}-\d{4}$)/.test("90210");

Some countries use Postal Codes, which would fail this pattern.

function isValidUSZip(sZip) {
   return /^\d{5}(-\d{4})?$/.test(sZip);
}

Here's a JavaScript function which validates a ZIP/postal code based on a country code. It allows somewhat liberal formatting. You could add cases for other countries as well. Note that the default case allows empty postal codes since not all countries use them.

function isValidPostalCode(postalCode, countryCode) {
    switch (countryCode) {
        case "US":
            postalCodeRegex = /^([0-9]{5})(?:[-\s]*([0-9]{4}))?$/;
            break;
        case "CA":
            postalCodeRegex = /^([A-Z][0-9][A-Z])\s*([0-9][A-Z][0-9])$/;
            break;
        default:
            postalCodeRegex = /^(?:[A-Z0-9]+([- ]?[A-Z0-9]+)*)?$/;
    }
    return postalCodeRegex.test(postalCode);
}

FYI The second link referring to vanity ZIP codes appears to have been an April Fool's joke.

If you're doing for Canada remember that not all letters are valid

These letters are invalid: D, F, I, O, Q, or U And the letters W and Z are not used as the first letter. Also some people use an optional space after the 3rd character.

Here is a regular expression for Canadian postal code:

new RegExp(/^[abceghjklmnprstvxy][0-9][abceghjklmnprstvwxyz]\s?[0-9][abceghjklmnprstvwxyz][0-9]$/i)

The last i makes it case insensitive.

Here's one from jQuery Validate plugin's additional-methods.js file...

jQuery.validator.addMethod("zipUS", function(value, element) {
    return /(^\d{5}$)|(^\d{5}-\d{4}$)/.test(value);
}, "Please specify a valid US zip code.");

---

EDIT: Since the above code is part of the jQuery Validate plugin, it depends on the .addMethod() method.

Remove dependency on plugins and make it more generic....

function checkZip(value) {
    return (/(^\d{5}$)|(^\d{5}-\d{4}$)/).test(value);
};

Example Usage: http://jsfiddle.net/5PNcJ/