I have this simpel ajax call to a php page.
$(document).ready(function(){
     $('#imgUpload').on('change', function () {
        $.ajax({
            url: './php/dataUpload.php',  
            type: 'POST',
            data: {boxId: boxId },
            dataType: "html",
            success: function(data){
                var box = $(data);
                alert('Do it!');
            },
        });
    });
});
On change the js-code will executed and I get a response from the php code. I don't know why however the result is the whole php code and not only the echo's..
The php code is:
<?php
    if(isset($_POST['boxId'])){
        echo $_POST['boxId'];
    } else {
        echo "blub";
    }
?> 
It's on a local server. Calling the php code only will echo "blub" to the browser-window so the php-code works.
Here the result of the ajax call if changed it to <?php echo "blub"; ?>: 
"<?php↵ echo "blub";↵?>"
