How to use regular javascript Ajax call JSF backend controller’s method

As everyone may known. Regular PrimeFaces-13 Ajax framework not support page level event such as “unload” or “beforeunload” when user is leaving current page in browser.

my javascript as:

<h:head>
  <title>Customer Details View</title>
  <meta name="viewport" content="initial-scale=1.0, user-scalable=no"/>
  <script type="text/javascript">
    $(window).unload(function () {
        $.ajax({
            type: 'GET',
            async: false,
            url: '#{customerSWController.leavingCustomerView()}'
        });
    });
  </script>
</h:head>

in my xhtml file

I’m trying to use header javascript to catch page “unload” event and then call my JSF backend bean method such as: #{backendController.leaveViewPage()} that I did it in p:ajax tag.

but unfortunately, I never get it works.

Any one have idea, please let me know.