66 lines
2.6 KiB
JavaScript
66 lines
2.6 KiB
JavaScript
'use strict';
|
|
// Simple offline service worker.
|
|
//
|
|
// On the main page include:
|
|
// if ('serviceWorker' in navigator)
|
|
// navigator.serviceWorker.register('simple-offline-service-worker.js');
|
|
//
|
|
// This cache always requests from the network to keep the cache fresh. There is a tradeoff here
|
|
// because it'll wait ages for a slow network despite having a cached response ready to go. If stale
|
|
// content is acceptable, use an 'eventually fresh' approach as described by Jake Archibald or
|
|
// Nicolás Bevacqua in https://ponyfoo.com/articles/progressive-networking-serviceworker
|
|
|
|
var version = 'v4.2.0';
|
|
|
|
// To cache https://yoururl/subdirectory/ without listing index.html, use './'. If using a manifest,
|
|
// 'start_url' should also be './'. You can also add additional files to this list.
|
|
var offlineFiles = [ './' ];
|
|
|
|
self.addEventListener('install', function(event) {
|
|
// Cache our list of files.
|
|
event.waitUntil(
|
|
caches.open(version).then(function(cache) {
|
|
return cache.addAll(offlineFiles).then(function() {
|
|
return self.skipWaiting();
|
|
});
|
|
})
|
|
);
|
|
});
|
|
|
|
// Remove any stale cache entries.
|
|
self.addEventListener('activate', function(event) {
|
|
event.waitUntil(
|
|
caches.keys().then(function(keys) {
|
|
return Promise.all(keys.map(function(key) {
|
|
if (key !== version)
|
|
return caches.delete(key);
|
|
}));
|
|
})
|
|
);
|
|
});
|
|
|
|
self.addEventListener('fetch', function(event) {
|
|
event.respondWith(
|
|
// FIXME: We should send off the fetch request and check the cache in parallel.
|
|
fetch(event.request).then(function(networkReponse) {
|
|
// Check if this request is already in our cache. We only want to cache previously
|
|
// cached items to prevent the cache from getting polluted.
|
|
return caches.open(version).then(function(cache) {
|
|
return cache.match(event.request).then(function(cachedResponse) {
|
|
if (!cachedResponse)
|
|
return networkReponse;
|
|
// Clone the response since we're also returning it below.
|
|
cache.put(event.request, networkReponse.clone());
|
|
return networkReponse;
|
|
});
|
|
});
|
|
}).catch(function(networkError) {
|
|
return caches.open(version).then(function(cache) {
|
|
return cache.match(event.request).then(function(cachedResponse) {
|
|
return cachedResponse || networkError;
|
|
});
|
|
});
|
|
})
|
|
);
|
|
});
|