check for online/offline events if fetching should be enabled

background/index.js

@@ -57,7 +57,29 @@ const fetchNewData = () => {
   });
 };
 
-fetchNewData();
-setInterval(() => {
+let intervalHandler = null;
+
+const stopFetching = () => {
+  if (intervalHandler !== null) {
+    clearInterval(intervalHandler);
+    intervalHandler = null;
+  }
+};
+const startFetching = () => {
   fetchNewData();
-}, Config.refreshTimeout);
+  if (intervalHandler === null) {
+    intervalHandler = setInterval(() => {
+      fetchNewData();
+    }, Config.refreshTimeout);
+  }
+};
+
+window.addEventListener('offline', () => {
+  stopFetching();
+});
+window.addEventListener('online', () => {
+  startFetching();
+});
+if (window.navigator.onLine) {
+  startFetching();
+}