Passing variable Javascript to PHP

gistfile1.txt

<!-- BEGIN HTML-->
<form>
    <div id="textBox" contenteditable="true" name="textBox"><?php echo $storyText; ?>
    </div>
    <textarea id="hiddeninput" name="hiddeninput"></textarea>
    <input type="submit" id="save" name="save" value="Submit"/>
</form>
<!-- END HTML-->

<!-- BEGIN Javascript-->
$('#save').click(function () {
    var mysave = $('#textBox').html();
    $('#hiddeninput').val(mysave);
    $("form:first").submit();
    $('#hiddeninput').append(mysave);
    alert($('#hiddeninput').val());
});
<!-- END Javascript-->