Specify ABSPATH in jQuery url

Question

I'm building a custom jQuery form and I need to specify the siteurl in the url that loads /wp-admin/admin-ajax.php.

I place this code in the template that has the form:

<script type="text/javascript">
jQuery('#newFeedbackForm').submit(ajaxSubmit); 
function ajaxSubmit(){
    var newFeedbackForm = jQuery(this).serialize();
    jQuery.ajax({
        type:"POST",
        url: <?php get_bloginfo('siteurl'); ?> . "/wp-admin/admin-ajax.php",
        data: newFeedbackForm,
        success:function(data){
            jQuery("#feedback").html(data);
        }
    });
    return false;
}
</script>

When I submit the form I get a 404 error with all the form inputs in the URL. I'm thinking ajax isn't being called right to handle the form and apply the function of the hidden value:

<input type="hidden" name="action" value="addComment"/>

Working backwards, here is the addComment function:

function addComment(){
global $wpdb;

$topic = $_POST['topic'];
$name = $_POST['name'];
$email = $_POST['email'];
$no_results_comment = $_POST['no_results_comment'];

// EXTRA
$date = time(); // UNIX TIMESTAMP

if($wpdb->insert('wp_no_results_feedback',array(
    'topic' => $topic,                                                      
    'name' => $name,
    'email' => $email,
    'no_results_comment' => $no_results_comment,
    'date' => $date
    ))===FALSE){
        echo "Error";           
    }else{
        echo "Thanks for your feedback. We will get back to you shortly.";
    }
    die();
}
add_action('wp_ajax_addComment','addComment');
add_action('wp_ajax_nopriv_addComment','addComment');

Answer 1

If your JavaScript is running in the admin, you don't need to set an explicit path to admin-ajax.php. It's always available as a JS variable called "ajaxurl". You can see an example of this in the Codex, under the heading "AJAX on the Administration Side"

Ajaxurl is, unfortunately, not available on the frontend by default. But you can use a trcik with wp_localize_script() to declare it in a custom namespace, and use it in your frontend scripts. This is a really handy trick. More in this blog post (also linked from that Codex article).

Answer 2

Following @MathSmath 's answer, you can make ajaxurl available in the front end using this snippet:

add_action('wp_head','pluginname_ajaxurl');
function pluginname_ajaxurl() {
    ?>
    <script type="text/javascript">
        var ajaxurl = '<?php echo admin_url('admin-ajax.php'); ?>';
    </script>
    <?php
}

And you need to pass the action name to the jQuery.ajax function as follows:

jQuery.ajax({
    action: 'addComment'
    type:"POST",
    data: newFeedbackForm,
    success:function(data){
        jQuery("#feedback").html(data);
    }
});