How to use blockUI with setTimeout and preventDefault on form submit?

Question

Here is shortly what I am doing and why:

1. I have a form, which is preprocessed with different scripts according user input
2. Usually script is executed in less than seconds, however one script may take around 10 seconds depending on server load etc.
3. Now I want to implement this "popup" containing: "Please wait while..." Im using blockUI for that - simple plugin for implementing this.
4. However, blockUI for fast script execution is quite stupid, as user will only see the popup flashing on the screen.
5. Therefore I want to set timeout for it, like 1000ms, so that blockUI is displayed even though form would have been already completed
6. So far I've tried quite many things, now I basically use preventDefault to cancel form submit for the setTimeout, but Im unable to complete the form submit after that.

Edit: Found out, that as javascript is asynchronous language, without preventDefault (stop form submitting) setTimeout never launches and action returns true straight away.

<form method="post" name="my_form" id="my_form" enctype="multipart/form-data">
    <input type="submit" name="my_submit" id="my_submit" value="Submit" />
    <div id="form_loading_message" style="display:none;"> 
        <h1>Please wait, page is loading...</h1> 
    </div>
</form>

$('#my_submit').click(function(event) {
    $.blockUI({
        message: $('#form_loading_message')
    });
    var form = $('#my_form');
    event.preventDefault();
    setTimeout(function () {
        form.unbind('submit').submit();
        $.unblockUI();
    }, 1000);
});

If you have better idea how to do this, please, I'm open for other suggestions aswell...

Answer 1

As I didnt find out how to do this with javascript, I used php sleep() -function before redirecting user to another page. Naturally preventDefault needed to be removed as it blocked the submit action. This solution solves the use case for me: Just to display user a message that the page is loading.