detecting when the "File download" popup is closed

No such event exists. You need to take a different approach to solve this.

1. target the download link to a hidden iframe with a name (target="myhiddeniframe")
2. on click of the download link, show your loading spinner
3. set the onload attribute of the iframe to a callback that hides your spinner

Net effect: you "spin" while the pdf is generated, and "unspin" when the "File download" dialog appears (as opposed to when the "File download" dialog is closed).

I am very sure that the answer is no, unless you want to consider some sort of ActiveX plugin to the browser (in which case the answer might still be no...)

I had to work on this kind of issue, on another project. I finally found a smart solution, as explained in another Stackoverflow question.

The explanation is given in the following post: http://gruffcode.com/2010/10/28/detecting-the-file-download-dialog-in-the-browser

The idea is to "simply" use a cookie to define when the file is downloaded.

• open your waiting popup
• do an AJAX query to generate the file, which returns the URL to that file
• in the AJAX query callback, close your waiting popup then redirect to the file URL

Example:

$('.generate_file_asynchronously').click(function(){
    var url = $(this).attr('href');

    show_loading_message();

    $.get(url, function(file_url) {
        hide_loading_message();
        window.location.href = file_url;
    });

    return false;
});