Is There Any Event/way We Can Know When A File Has Finished Downloading?

This question has been asked a much time, but I am unable to get a perfect answer to implement. So I give it a try asking one more time. Suppose you wish to show a message when you

Solution 1:

When you request a file from your server, send a unique key to the download service from the client.

GET /Download?fileId=someId&cookieName=abc

When the server has finished serving the file contents, set a cookie with the unique name

var cookieName = Request.QueryString["cookieName"]; 
Response.Cookies.Add(new HttpCookie(cookieName , "true")
{
    Path = "/",
    HttpOnly = false
});

Meanwhile, in your JavaScript, listen for a cookie with your unique name on it and once it is set, do a callback:

window.setInterval(function () {
    var cookie = $.cookie('abc');
        if (cookie !== null) {
            callback();
        }
}, 500);

You might also want to look into deleting the cookie when you are done.