Service Worker file offline events - push-notification

Question

Google Chrome latest(v55.0.2883.87)
There are various event in that (sw.js)file. Everytime a file got requested fetch event occur. How and when other events occur(sync, push)(web notification api). I want to debug it. Is there any doc available?
Update:
server-key-from-firebase-console
subscription-key-after-subscribing-web-notification
Found how push notification fired--
String url = "https://fcm.googleapis.com/fcm/send";
URL obj = new URL(url);
HttpsURLConnection con = (HttpsURLConnection) obj.openConnection();
//add reuqest header
con.setRequestMethod("POST");
con.setRequestProperty("Authorization", "key=<server-key-from-firebase-console>");
con.setRequestProperty("Content-Type", "application/json");
String urlParameters = "{\"to\":\"<subscription-key-after-subscribing-web-notification>\"}";
// Send post request
con.setDoOutput(true);
DataOutputStream wr = new DataOutputStream(con.getOutputStream());
wr.writeBytes(urlParameters);
wr.flush();
wr.close();
int responseCode = con.getResponseCode();
System.out.println("\nSending 'POST' request to URL : " + url);
System.out.println("Post parameters : " + urlParameters);
System.out.println("Response Code : " + responseCode);
BufferedReader in = new BufferedReader(
new InputStreamReader(con.getInputStream()));
String inputLine;
StringBuffer response = new StringBuffer();
while ((inputLine = in.readLine()) != null) {
response.append(inputLine);
}
in.close();
//print result
System.out.println(response.toString());
Update 2:
Ok now i found how to fire a sync event in service worker file either from google chrome debugger tool or from javascript. Below is the code, what i have found on google's blog post.
// Register your service worker:
navigator.serviceWorker.register('/sw.js');
// Then later, request a one-off sync:
navigator.serviceWorker.ready.then(function(swRegistration) {
return swRegistration.sync.register('myFirstSync');
});
Then listen for the event in /sw.js:
self.addEventListener('sync', function(event) {
if (event.tag == 'myFirstSync') {
event.waitUntil(doSomeStuff());
}
});

Answer 1

A good resource for knowing more about ServiceWorker is MDN (Mozilla Developer Network).
Here is the entry point to the documentation related to ServiceWorker:
https://developer.mozilla.org/en-US/docs/Web/API/Service_Worker_API
There you have links and explanations for the install, fetch, sync and push events. And the new ones that will appear like background sync will be documented there too.
Happy reading.