as per Adding a “loading” image to (just about) any form on submit, with jQquery

add ajax style loading image to any form

<script language="javascript" type="text/javascript">
$("form").submit(function() {
if ($('#loading_image').length == 0) { //is the image on the form yet?
                // add it just before the submit button
$(':submit').before('<img src="/images/ajax-loader.gif" style="display: none;" alt="loading" id="loading_image">')
}
    $('#loading_image').show(); // show the animated image    
    $(':submit',this).attr('disabled','disabled'); // disable double submits
    return true; // allow regular form submission
});
</script>

all explained at http://www.falsepositives.com/index.php/2010/08/16/show-a-loading-image-to-any-form-with-ajax-and-jquery/ Adding a “loading” image to (just about) any form on submit, with jQquery