How we call logout servlet on browser close event

Question

How can I handle the close event of a browser to trigger a logout?

Answer 1

I've searched for a consistent solution to this problem some time ago, and my decision was to handle the situation without believing the browser or the user.

You can't for sure know if a user is leaving your page and when, and even if you use 'onunload', you may not get the event before the browser closes or leaves your page. And browser crashes won't give you any kind of signal, so believing you know the user is still viewing you page and may take any further action is flawed.

The best you can do about logging out an user is put a fitting session timeout, and if you need further control, you may try adding AJAX calls on critical pages with 'I'm alive' signals, and then logging out users that are not responding anymore (that would require AJAX/JS enabled browser and may exclude potential users).

Answer 2

You're looking for the onunload:

window.onunload = function() {
  // check the window is closed (see point 1 below)
  // do log out
}

There are 2 problems with this:

1. It's called whenever the user navigates away from the page, refreshes, or generally unloads as well as when the browser window is closed.
2. There doesn't seem to be a consistent behaviour between browsers.

I recommend using a different approach.