Address Validation using the Google Maps API

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <title>Example Form </title>
    <link href="./css/site.css" rel="stylesheet" type="text/css" />
    <script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.4.2/jquery.min.js"></script>
    <script type="text/javascript" src="http://ajax.microsoft.com/ajax/jquery.validate/1.7/jquery.validate.min.js"></script>
    <script src="http://maps.google.com/maps/api/js?sensor=false" type="text/javascript"></script>
</head>
<body>
    <div class="page">
        <div id="main">
            <form id="MyForm" name="MyForm" action="form.html">
                <div id="map_canvas" style="float: right; height: 200px; width: 400px;"></div>
                <div>
                    <label for="Name">
                        Name</label>
                    <input id="Name" name="Name" type="text" />
                </div>
                <div>
                    <label for="FullAddress">
                        Address</label>
                    <textarea id="FullAddress" name="FullAddress" cols="40" rows="5" class="fulladdressvalidator"></textarea>
                </div>
                <div>
                    <input id="Submit" name="Submit" value="Submit" type="button" />
                </div>
            </form>
        </div>
    </div>
    <script type="text/javascript">
        // The following code show execute only after the page is fully loaded
        $(document).ready(function () {
            if ($('#MyForm').exists()) {

                // Enable jQuery Validation for the form
                $("#MyForm").validate({ onkeyup: false });

                // Add validation rules to the FullAddress field
                $("#FullAddress").rules("add", {
                    fulladdress: true,
                    required: true,
                    messages: {
                        fulladdress: "Google cannot locate this address."
                    }
                });

                // This function will be executed when the form is submitted
                function FormSubmit() {
                    $.submitForm = true;
                    if (!$('#MyForm').valid()) {
                        return false;
                    } else {
                        if ($("#FullAddress").data("IsChecking") == true) {
                            $("#FullAddress").data("SubmitForm", true);
                            return false;
                        }

                        alert('Form Valid! Submit!');
                        // return true; // Uncomment to submit the form.
                        return false; // Supress the form submission for test purpose.
                        
                    }
                }

                // Attach the FormSubmit function to the Submit button
                if ($('#Submit').exists()) {
                    $("#Submit").click(FormSubmit);
                }

                // Execute the ForumSubmit function when the form is submitted
                $('#MyForm').submit(FormSubmit);
            }
        });

        // Create a jQuery exists method
        jQuery.fn.exists = function () { return jQuery(this).length > 0; }

        // Position the Google Map
        function Map(elementId, geolocation) {
            var myOptions = {
                zoom: 13,
                mapTypeId: google.maps.MapTypeId.ROADMAP
            }
            var map = new google.maps.Map(document.getElementById(elementId), myOptions);
            map.setCenter(geolocation);
        }

        // FullAddress jQuery Validator
        function FullAddressValidator(value, element, paras) {

            // Convert the value variable into something a bit more descriptive
            var CurrentAddress = value;

            // If the address is blank, then this is for the required validator to deal with.
            if (value.length == 0) {
                return true;
            }

            // If we've already validated this address, then just return the previous result
            if ($(element).data("LastAddressValidated") == CurrentAddress) {
                return $(element).data("IsValid");
            }

            // We have a new address to validate, set the IsChecking flag to true and set the LastAddressValidated to the CurrentAddress
            $(element).data("IsChecking", true);
            $(element).data("LastAddressValidated", CurrentAddress);

            // Google Maps doesn't like line-breaks, remove them
            CurrentAddress = CurrentAddress.replace(/\n/g, "");

            // Create a new Google geocoder
            var geocoder = new google.maps.Geocoder();
            geocoder.geocode({ 'address': CurrentAddress }, function (results, status) {

                // The code below only gets run after a successful Google service call has completed.
                // Because this is an asynchronous call, the validator has already returned a 'true' result
                // to supress an error message and then cancelled the form submission. The code below
                // needs to fetch the true validation from the Google service and then re-execute the
                // jQuery form validator to display the error message. Futhermore, if the form was
                // being submitted, the code below needs to resume that submit.

                // Google reported a valid geocoded address
                if (status == google.maps.GeocoderStatus.OK) {

                    // Get the formatted Google result
                    var address = results[0].formatted_address;

                    // Count the commas in the fomatted address.
                    // This doesn't look great, but it helps us understand how specific the geocoded address
                    // is. For example, "CA" will geocde to "California, USA".
                    numCommas = address.match(/,/g).length;

                    // A full street address will have at least 3 commas. Alternate techniques involve
                    // fetching the address_components returned by Google Maps. That code looks even more ugly.
                    if (numCommas >= 3) {

                        // Replace the first comma found with a line-break
                        address = address.replace(/, /, "\n");

                        // Remove USA from the address (remove this, if this is important to you)
                        address = address.replace(/, USA$/, "");

                        // Check for the map_canvas, if it exists then position the Google Map
                        if ($("#map_canvas").exists()) {
                            $("#map_canvas").show();
                            Map("map_canvas", results[0].geometry.location);
                        }

                        // Set the textarea value to the geocoded address
                        $(element).val(address);

                        // Cache this latest result
                        $(element).data("LastAddressValidated", address);

                        // We have a valid geocoded address
                        $(element).data("IsValid", true);
                    } else {
                        // Google Maps was able to geocode the address, but it wasn't specific
                        // enough (not enough commas) to be a valid street address.
                        $(element).data("IsValid", false);
                    }

                    // Otherwise the address is invalid
                } else {
                    $(element).data("IsValid", false);
                }

                // We're no longer in the midst of validating
                $(element).data("IsChecking", false);

                // Get the parent form element for this address field
                var form = $(element).parents('form:first');

                // This code is being run after the validation for this field,
                // if the form was being submitted before this validtor was
                // called then we need to re-submit the form.
                if ($(element).data("SubmitForm") == true) {
                    form.submit();
                } else {
                    // Re-validate this property so we can return the result.
                    form.validate().element(element);
                }
            });

            // The FullAddress validator always returns 'true' when initially called.
            // The true result will be return later by the geocode function (above)
            return true;
        }

        // Define a new jQuery Validator method
        $.validator.addMethod("fulladdress", FullAddressValidator);
    </script>
</body>
</html>
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