Is it possible to catch browser's File Open/Save dialog event using Javascript

Question

Using Javascript is it possible to listen for browser's file open/save dialog box event. I want to perform an action when I am notified that the save file dialog box has opened now. Specifically I want to hide a loading spinner when dialog box opens (but this could very well be any other action )

I believe I can do that for a dialog box that I create, not sure if it can be done for the browser's standard dialog box.

Any pointers for that would be really helpful.

Solution 1

No, there is no event for that.

Solution 2

Yes! You can take advantage that most browsers (Tested okay on Chrome, Firefox, and IE) fire the beforeunload event just before the Individual-file Download dialog opens.

So code like this will work:

$(window).bind ("beforeunload",  function (zEvent) {
    // PERFORM DESIRED ACTIONS HERE.
    /* This code will fire just before the Individual-file Download 
       dialog opens.
       Note that it will also fire before the tab or window is closed, 
       but that should not be a problem for this application.
    */
} );

Open and run this snippet to see it in action:

$(window).bind ("beforeunload",  function (zEvent) {
    $("#dwnldStatus").text ("This code runs just before the file open/save dialog pops up.");
} );

$("#directDwnload").click ( function () {
    fireDownload ();
} );

$("#ResetTimer").click ( function () {
    $("#dwnldStatus").html (
        'Download will start in <span id="timeleft">3</span> seconds.'
    );
    fireTimer (3);
} );

function fireDownload () {
    window.location.assign (
        "//phs.googlecode.com/files/Download%20File%20Test.zip"
    );
}

function fireTimer (secondsLeft) {
    this.secondsLeft    = secondsLeft || 30;
    this.countdownTimer = this.countdownTimer || null;

    if ( ! this.countdownTimer) {
        this.countdownTimer = setInterval ( function() {
                this.secondsLeft--;
                $("#timeleft").text (this.secondsLeft);
                if (this.secondsLeft <= 0) {
                    clearInterval (this.countdownTimer);
                    this.countdownTimer = null;
                    fireDownload ();
                }
            },
            1000
        );
    }
}

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.0/jquery.min.js"></script>
<p>Activate one of the download buttons.  The timer button is just like any other javascript initiated download, no additional  click is needed.</p>
<p>The javascript detects when the File/Save dialog pops up and changes the status to "This code runs just before the file open/save dialog pops up.".</p>
<p>Note that it is not necessary to download the file. You can cancel the download.</p>

<div id="dwnldStatus"></div>
<button id="ResetTimer">Set timer to 3 seconds.</button>
<button id="directDwnload">Download the file now.</button>

---

Note that beforeunload will also fire before the tab or window is closed, so plan accordingly. That should not be an issue for this question as stated.

Comments

[Darin Dimitrov]

Why a let down? I would say it's a very good thing which protects users privacy. +1 by the way.

[Matthew Flaschen]

I think he's talking about the regular File->Save, File->Open dialog boxes, and you can't watch e.g. the browser's toolbar or menubar.

[lazy functor]

I am talking about the dialog box you get when you download a file with content disposition as attachment. I think you can't watch that event. Thanks

[Brock Adams]

@BryanDowning, The beforeunload event will fire when that dialog opens.

[Matthew Flaschen]

@BrockAdams, that does hit one useful scenario. But it only works if they navigate to a zip, not if they hit Ctrl-O, Ctrl-S, right-click save image as, etc.

[Brock Adams]

@MatthewFlaschen, The question appears to be for the scenario when the page/app is preparing an individual file to download. Ctrl-O and Ctrl-S do not apply. Right-click would not apply either in the most common applications.

[Markiv]

This works as needed. Not sure why this answer is not rated high.