How to trigger a download prompt through post callback function

Question

simple question I guess, but can't figure it out... Here's the problem:

In the front end, I export some user-selected data to the server to dynamically create a file:

$("#export-button").click(function() {

$.post("'.$postUrl.'",{variable:exportSelection},
    function(data) {
        console.log(data);
    }
);});

Then, after I receive the data and create/save the file on the server, I am doing the following in php:

if (file_exists($file)) {
    header('Content-Description: File Transfer');
    header('Content-Type: application/octet-stream');
    header('Content-Disposition: attachment; filename='.basename($file));
    header('Expires: 0');
    header('Cache-Control: must-revalidate');
    header('Pragma: public');
    header('Content-Length: ' . filesize($file));
    ob_clean();
    flush();
    readfile($file);
    exit;}

What am I supposed to do in the post callback function instead of printing on the console in order to get a download prompt?

UPDATE: OK - I just realised that my #export-button was an anchor tag with no href... Now when I point to the file on the server, the problem is that when I click, it follows the link prompts to save file etc., but it gets to the file BEFORE the "new" version is generated (so using the previous selection at each click)

Answer 1

OK - I figured it out. I just needed to disable the link from pointing anywhere and then do:

window.location = 'my_file_location.doc';

... inside the callback function