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sw.js
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sw.js
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---
layout: null
---
// Cache all css
//
const raw = [
"/",
"https://ghbtns.com/github-btn.html?user=dfahlander&repo=Dexie.js&type=star&count=true",
"https://api.github.com/repos/dfahlander/Dexie.js",
"https://buttons.github.io/buttons.js",
"https://unpkg.com/dexie",
"https://www.google-analytics.com/analytics.js",
{% for page in site.html_pages %}
"{{ page.url }}",
{% endfor %}
{%for file in site.static_files %}
"{{ file.path }}",
{% endfor %}
].filter(file =>
!file.startsWith("/test") &&
!file.includes("analytics.js") &&
!file.endsWith(".sh") &&
!file.startsWith("/assets/movies/"));
const CACHE_NAME = 'dexiejs-offline-cache';
async function waitForAll(promises){
return new Promise( resolve => {
let rc = { success: 0, failure:0 };
for (let i=0; i < promises.length; i++) {
promises[i]
.then(()=>{
rc.success++;
if (rc.success+rc.failure === promises.length) resolve(rc);
}).catch(err => {
rc.failure++;
if (rc.success+rc.failure === promises.length) resolve(rc);
console.error(`error occurred ${err}`);
});
}
});
}
/*
function isCurrentSite(url){
const u = new URL(url);
if (self.location.origin === u.origin){
return true;
}
return false;
}
function shortIfLocal(url){
const u = new URL(url);
if (isCurrentSite(u)) {
return u.pathname;
}
return u.href;
}
function correctUrlForLocal(url){
// try to construct url
let temp;
try{
temp = new URL(url);
} catch (err) {
try {
temp = new URL(self.location.origin+url);
}
catch(err2){
temp = undefined;
}
}
if (!temp) return url;
if (!isCurrentSite(temp)) return temp;
temp.pathname = temp.pathname.replace(/\/$/,'');
return temp;
}*/
self.addEventListener('install', function (event) {
event.waitUntil(
caches.delete(CACHE_NAME)
.then(() => caches.open(CACHE_NAME))
.then(async cache => {
console.log('Opened cache');
const leadingSlashRemoved = raw.map(url => url);
do {
// cache in batches of 10
const sliceDice = leadingSlashRemoved.splice(0, 50);
await waitForAll(sliceDice.map(async url => {
const response = await fetch(url);
console.log("URL", url, response);
await cache.put(url, response);
}));
} while(leadingSlashRemoved.length > 0);
return true;
})
);
});
const MAX_WAIT = 300; // If network responds slower than 100 ms, respond with cache instead
self.addEventListener('fetch', function (event) {
const request = event.request;
// Don't take over if it's not a GET, HEAD or OPTIONS request
if (request.method !== 'GET' && request.method !== "HEAD" && request.method !== "OPTIONS") return;
// Don't cache google analytics requests:
if (/google-analytics/.test(request.url)) return;
// Start reading from cache
const cachedResponsePromise = caches.match(request, {ignoreVary: true});
const fetchPromise = fetch(request);
let timeoutHandle;
const timeoutPromise = new Promise(resolve => {
timeoutHandle = setTimeout(()=>{
timeoutHandle = null;
resolve("timedout");
}, MAX_WAIT)
});
// Start fetching in parallell
event.respondWith(Promise.race([fetchPromise, timeoutPromise]).then(async res => {
if (timeoutHandle) clearTimeout(timeoutHandle);
// Fetch successful, probably online. See if we also have the cached response:
const cachedResponse = await cachedResponsePromise.catch(err => null);
if (res === "timedout" || !res.ok) {
// Fetch didn't throw but the result wasn't ok either.
// Could be timeout, a 404, 500 or maybe offline?
// In case we have an OK response in the cache, respond with that one instead:
if (cachedResponse && cachedResponse.ok) {
// Respond from cache.
// But in parallell, update the cache once the slow response arrives (if it is successful and newer)
if (res === "timedout") {
console.debug("URL", request.url, "timedout. Serving it from cache but also update cache once slow response arrives");
event.waitUntil(fetchPromise.then(async res => {
if (!res.ok) return;
await updateCache(request, res, cachedResponse);
}).catch(err => null));
}
return cachedResponse;
} else if (res === "timedout") {
// We don't have anything in cache. Wait for fetch even if it takes time.
res = await fetchPromise;
if (!res.ok) {
// Response not successful. Respond with it without trying to cache it.
return res;
}
// else, the slow response was successful. Let it continue further down
// so we can cache this slow response.
} else {
// res not ok. Don't cache it but return it.
return res;
}
}
// We come here if the real fetch was successful.
event.waitUntil(updateCache(request, res, cachedResponse));
return res;
}, async error => {
const cachedResponse = await cachedResponsePromise.catch(err => null);
console.debug("sw: Finding in cache:", request.url, cachedResponse);
console.debug("sw: ok?:", cachedResponse && cachedResponse.ok);
if (cachedResponse && cachedResponse.ok) {
return cachedResponse;
}
throw error;
}));
});
async function updateCache(request, res, currentCachedRes) {
// Should we update the cache with this fresh version?
let cachedLastMod = currentCachedRes && currentCachedRes.headers.get("last-modified");
if (!cachedLastMod || (cachedLastMod !== res.headers.get("last-modified"))) {
// There were no cached response, or no "last-modified", or "last-modified" headers was changed - keep the cache up-to-date,
// so that, when the user goes offline, it will have the latest and greatest, and not revert to old versions
const clonedResponse = res.clone();
const cache = await caches.open(CACHE_NAME);
await cache.put(request, clonedResponse);
}
}