JavaScript Backend Ping Online Check Worker (AngularJS)

main.js

var pingWorker = new Worker('ping_worker.js');

pingWorker.addEventListener('message', function(event) {
  if($scope.online != event.data) {
    $scope.online = event.data;
    $scope.$apply();
  }
  console.log('Are we online?', event.data);
}, false);

// worker starten
pingWorker.postMessage();

ping_worker.js

self.checkOnline = function() {
	var xhr = new XMLHttpRequest();
	xhr.open('GET', 'http://localhost:8080/portal/resources/monitor/version', true);
	xhr.onreadystatechange = function (oEvent) {  
	    if (xhr.readyState === 4) {  
	        if (xhr.status === 200) {  
	        	self.postMessage(true);
	        } else {  
	        	self.postMessage(false);
	        }  
	    }  
	};  
	xhr.send(null);  
}

self.addEventListener('message', function(event) {
	checkOnline();
	setInterval("checkOnline()", 10000);
}, false);