ASF Board Agenda service worker

sw.js

//
// A very simple service worker
//
//   1) Create an event source and pass all events received to all clients
//
//   2) Return back cached bootstrap page instead of fetching agenda pages
//      from the network.  Bootstrap will construct page from cached
//      agenda.json, as well as update the cache.
//
//   3) For all other pages, serve cached content when offline
// 
var events = null;

this.addEventListener("activate", function(event) {
  // close any pre-existing event socket
  if (events) {
    try {
      events.close()
    } catch (e) {
      events = null
    }
  };

  // create a new event source
  events = new EventSource("events");

  // dispatch any events received to clients
  events.addEventListener("message", function(event) {
    clients.matchAll().then(function(list) {
      list.forEach(function(client) {
        client.postMessage(event.data)
      })
    })
  })
});

this.addEventListener("fetch", function(event) {
  var scope = this.registration.scope;
  var url = event.request.url;
  if (url.substring(0, scope.length) == scope) url = url.slice(scope.length);

  if (new RegExp("^\\d\\d\\d\\d-\\d\\d-\\d\\d/").test(url) && event.request.method == "GET") {
    event.respondWith(caches.open("board/agenda").then(function(cache) {
      var date = url.split("/")[0];

      return cache.match(date + "/bootstrap.html").then(function(response) {
        return response || fetch(event.request.url, {credentials: "include"})
      })
    }))
  } else {
    event.respondWith(fetch(event.request, {credentials: "include"}).catch(function(error) {
      return caches.open("board/agenda").then(function(cache) {
        return cache.match(event.request, function(response) {
          return response || error
        })
      })
    }))
  }
})