In goapp.js activate should remove old cache.

[bgokden]

When a service worker updated due to a new version released. New versions of the files should be cached and old ones should be removed.

Google has a recommended way of doing this explained here:
https://developers.google.com/web/fundamentals/primers/service-workers#update-a-service-worker

We can change activate the function to this if you accept I would like to create a pull request.

self.addEventListener('activate', function(event) {
  
  console.log('goapp worker', etag, 'is activated')

  var cacheWhitelist = [
        {{range .Paths}}'{{.}}',
        {{end}}'/'
      ];

  event.waitUntil(
    caches.keys().then(function(cacheNames) {
      return Promise.all(
        cacheNames.map(function(cacheName) {
          if (cacheWhitelist.indexOf(cacheName) === -1) {
            return caches.delete(cacheName);
          }
        })
      );
    })
  );
});

[maxence-charriere]

Hi @bgokden , thank you for pointing this.

Look like your snippet does not use the right values to put in cache white list. It appears it takes caches names rather than paths.

Also goapp is using only one cache so it will never be deleted.
I think having the code that already match what is suggested by google is a good to have, especially if in the future we decide to use another cache or rename the current one.

I just got a PR that add this part.

Thanks you again.

[maxence-charriere]

Also this is an open source project, if you think you have a fix or an improvement, feel free to open a PR.
I ll review it :).