unregister service worker

src/index.js

@@ -2,7 +2,13 @@ import React from 'react';
 import ReactDOM from 'react-dom';
 import './index.css';
 import App from './App';
-import registerServiceWorker from './registerServiceWorker';
+//import registerServiceWorker from './registerServiceWorker';
 
 ReactDOM.render(<App />, document.getElementById('root'));
-registerServiceWorker();
+//registerServiceWorker();
+if(navigator.serviceWorker && navigator.serviceWorker.getRegistrations)
+    navigator.serviceWorker.getRegistrations()
+        .then(function(registrations) {
+            for(let registration of registrations) {
+                registration.unregister();
+        }});