Sends events to analytics in timeouts to improve session tracking

leaveSessionTracker.js

window.addEventListener('beforeunload',
 function(){
  ga('send', 'event', 'Website', 'Unload', {transport: 'beacon', nonInteraction:true});
 }
);

var timeout = 1;
var startTime = new Date().getTime();
function startBeacon() {
  var timeOnSite = (startTime - new Date().getTime()) / 1000;
  var delay;
  if (timeOnSite < 5) {
    delay = 3;
  } else if (timeOnSite < 60) {
    delay = 5;
  } else if (timeOnSite < 240) {
    delay = 10;
  } else {
    delay = 30;
  }
  
  setTimeout(function(){ 
    ga('send', 'event', 'Website', 'Ping', {nonInteraction:true});
    startBeacon();
  }, delay * 1000);
}
startBeacon();