Passing a variable from PHP to javascript and on to an html form

I'm having one, admittedly very minor issue with a contact form I've set up in WordPress using jQuery, jQuery form and PHP Mail to send a form-generated email.

To replace my current contact form which performs a pHp validation from within the contact form page and then sends using PHP Mail, I've designed the following simple html 5 form (which can be seen on this page: http://edge.donaldjenkins.net/contact):

<form id="contact" method="post" action="">
<fieldset>  

    <label for="name">Name</label>
    <input type="text" name="name" placeholder="Your Name" title="Enter your name" class="required">

    <label for="email">E-mail</label>
    <input type="email" name="email" placeholder="[email protected]" title="Enter your e-mail address" class="required email">

    <label for="phone">Phone</label>
    <input type="tel" name="phone" placeholder="ex. (555) 555-5555">

    <label for="website">Website</label>
    <input type="url" name="url" placeholder="http://">

    <label for="message">Question/Message</label>
    <textarea name="message"></textarea>

    <label for="checking" class="hidden">If you want to submit this form, do not enter anything in this field</label><input type="text" name="checking" class="hidden">

    <input type="submit" name="submit" class="button" id="submit" value="Send Message" />

</fieldset>

I then use the jQuery validate [jquery.validate.js] and form [jquery.form.js] plugins to perform a client-end validation:

<script src="js/jquery.validate.js"></script>
<script src="js/jquery.form.js"></script>

<script>
$(function(){
$('#contact').validate({
submitHandler: function(form) {
    $(form).ajaxSubmit({
    url: 'send-message.php',
    success: function() {
    $('#contact').hide();
    $('#instructions').hide();
    $('#status').show();
    $('#popular-posts').show();
    $('#status').append("<p>Thanks! Your request has been sent.  One will try to get back to you as soon as possible.</p>")
    }
    });
    }
});         
});
</script>

After the validation, the above script uses jQuery.form's ajaxSubmit function to submit the date to a server PHP page, send-message.php (the reason being that javascript can't send email). I use this PHP file to carry out a second, server-side validation of the data (though this is probably redundant, since because the setup relies on javascript to pass the data on to the server, one can safely assume that no one will be able to use the form without javascript enabled). It also performs a honeypot captcha check on data in a hidden input field added in the form. The email is then sent:

<?php 
//invoke wp_load in order to use WordPress wp_mail plugin function instead of mail for    better authentification of the sent email
require_once("/path/to/wp-load.php");

//Check to see if the honeypot captcha field was filled in
if(trim($_POST['checking']) !== '') {
$captchaError = true;
$errors .= "\n Error: Captcha field filled in";
} else {

//Check to make sure that the name field is not empty
if(trim($_POST['name']) === '') {
    $errors .= "\n Error: Name field empty";
    $hasError = true;
} else {
    $name = strip_tags($_POST['name']);
}

//Check to make sure sure that a valid email address is submitted
if(trim($_POST['email']) === '')  {
    $emailError = 'You forgot to enter your email address.';
    $hasError = true;
} else if (!eregi("^[A-Z0-9._%-]+@[A-Z0-9._%-]+\.[A-Z]{2,4}$", trim($_POST['email']))) {
    $errors .= "\n Error: Message field empty";
    $hasError = true;
} else {
    $email = strip_tags($_POST['email']);
}

//Check to make sure comments were entered  
if(trim($_POST['message']) === '') {
    $errors .= "\n Error: Message field empty";
    $hasError = true;
} else {
    $phone = strip_tags($_POST['phone']);
    $url = strip_tags($_POST['url']);
    if(function_exists('stripslashes')) {
        $message = stripslashes(trim($_POST['message']));
    } else {
        $message = strip_tags($_POST['message']);
    }
}
//If there is no error, send the email
if(!isset($hasError)) {

    // Send Message 
    $emailTo = '[email protected]';
    $subject = 'Contact Form Submission from '.$name;
    $body = "Name: $name \n\nEmail: $email \n\nPhone: $phone \n\nWebsite: $url \n\nMessage: $message";
    $headers = 'From: My Site <'.$emailTo.'>' . "\r\n" . 'Reply-To: ' . $email;

    wp_mail($emailTo, $subject, $body, $headers);

    $alert = 'Thanks! Your request has been sent.  One will try to get back to you as soon as possible.';
} else {
    $alert = $errors;
}
} ?>

The server keeps track of whether errors were found or whether the email was successfully sent in variable $alert.

After the pHp function completes, the script hides the form from the contact page and displays a previously hidden html element to which it appends an alert message.

The issue I can't solve is making javascript change the wording of that alert message to reflect whether the email was or not successfully sent, because I don't know how to pass the requisite pHp variable ($alert) containing a list of the error messages in the server PHP process to the script for insertion in the Contact Form page. Of course, again, this is a very theoretical concern, since for the reasons stated above, it's unlikely that an error-prone message would even have reached the PHP stage in the first place.

I've tried inserting the following code at the end of the PHP file, to no avail:

<script type="text/javascript">
alert = <?php echo $alert; ?>;
</script>

The latter attempt doesn't generate any errors in Firebug, but the variable value doesn't get passed on. Any ideas or thoughts welcome.

UPDATE: I added this workflow chart to clarify the setup for this issue: