Check is user logged in in interval of 10 sec

I have tried to write the following to check if a user’s session is valid… but it can’t seem to work. Do i have to do something to make is_user_logged_in() work?

<script>
function loadcheck() {
  setInterval(function(){ 
var login = is_user_logged_in()
  if ( login == true ) {
   alert("You are logged in");
  } else {
      alert("You have been logged out");
  }  }, 10000);
}</script>