How to know the time a user spends on a page in a Django Project

We can achieve this by using some Javascript library, 

Find below the high level draft version you can use it,And one more thing which is not related to Django Project alone, we can apply the same concept in any backend framework,

We can write our own Javascript like below,

$(document).ready(function() {
  var startDate = new Date();

  $(window).unload(function() {
      var endDate = new Date();
      $.ajax({ 
        type: POST,
        url: "/backendurl",
        data: {'timeSpent': endDate - startDate},
       
      })
   });
});

Or another approach is using TimeJS library to handle it

<script src="TimeMe.js"></script>
<script type="text/javascript">
TimeMe.initialize({
    currentPageName: "page you want", // page name
    idleTimeoutInSeconds: 15 // time before user considered idle
});
</script>

and push the data to Django backend using above Jquery POST call