Sanitize and validate ZIP codes in Magento using Prototype's Validation

sanitize_zip_fr.js

/**
 * A simple ZIP code validator and sanitizer
 *
 * @author Hervé Guétin <@herveguetin> <herve.guetin@agence-soon.fr>
 */
var zipSanitizer = {

    // All sanitizers available
    sanitizers: {},

    // Add a sanitizer
    add: function(o) {
        this.sanitizers[o.countryCode] = function() {

            // Add Prototype validation
            if(typeof o.validationRegex !== 'undefined') {
                Validation.add('sanitize-zip-' + o.countryCode, 'Please enter a valid zip code.', function(v) {
                    return Validation.get('IsEmpty').test(v) || o.validationRegex.test(v);
                });
            }

            // Append sanitizing function
            if(typeof o.sanitize !== 'undefined') {
                $$('.sanitize-zip-' + o.countryCode).each(function(el) {
                    o.sanitize(el);
                    el.observe('keyup', function() {
                        o.sanitize(el);
                    })
                });
            }
        };
    },

    // Sanitize a ZIP code input based on selected country
    sanitize: function(countryCode, zipInput) {

        // Remove any existing sanitizer on ZIP input element
        var currentClassNames = zipInput.classNames().toArray();
        currentClassNames.each(function(className) {
            if(className.indexOf('sanitize-zip-') > -1) {
                zipInput.removeClassName(className);
                zipInput.stopObserving('keyup');
            }
        });

        // Configure and sanitize ZIP input element
        zipInput.addClassName('sanitize-zip-' + countryCode);
        if(typeof this.sanitizers[countryCode] !== 'undefined') {
            this.sanitizers[countryCode]();
        }
    }
};

/**
 * Create a sanitizer for France
 */
zipSanitizer.add({
    countryCode: 'FR', // Country as in country_id element select options
    validationRegex: /^\d{5}$/, // Validation regex for Prototype Validation
    sanitize: function(el) { // What to do to make sure ZIP input is correct?
        var value = el.getValue();
        value = value.replace(/\D/g, '');
        value = value.substr(0, 5);
        el.setValue(value);
    }
});

/**
 * Once DOM is loaded...
 */
;document.observe("dom:loaded", function() {

    // Gather all country_id select of page
    var countryInputs = $$('[name="country_id"]');

    // For each country_id inputs...
    countryInputs.each(function(el) {

        // ... find its related ZIP input element
        var zipInput = el.up('div.fieldset').down('[name="postcode"]');

        // If there is country that is selected by default, sanitize it staight away!
        if(el.getValue() !== undefined && el.getValue() !== '') {
            zipSanitizer.sanitize(el.getValue(), zipInput);
        }

        // And make sure this ZIP input is sanitized on each country change
        el.observe('change', function() {
            zipSanitizer.sanitize(el.getValue(), zipInput);
        });
    });
});