sw.js

var GHPATH = "/potato-peace";
var APP_PREFIX = "peace_";
var VERSION = "version_0.08";
var URLS = [
    `${GHPATH}/`,
    `${GHPATH}/index.html`,
    `${GHPATH}/manifest.webmanifest`,
    `${GHPATH}/script.js`,
    `${GHPATH}/vn-runner.js`,
    `${GHPATH}/ink.js`,
    `${GHPATH}/story.js`,
    `${GHPATH}/style.css`,
    `${GHPATH}/img/about.png`,
    `${GHPATH}/img/ceremony.png`,
    `${GHPATH}/img/cover.png`,
    `${GHPATH}/img/father.png`,
    `${GHPATH}/img/mayor.png`,
    `${GHPATH}/img/mc.png`,
    `${GHPATH}/img/mc2.png`,
    `${GHPATH}/img/mc3.png`,
    `${GHPATH}/img/museum.png`,
    `${GHPATH}/img/office.png`,
    `${GHPATH}/img/restart.png`,
    `${GHPATH}/img/save.png`,
    `${GHPATH}/img/sculptor.png`,
    `${GHPATH}/img/statue.png`,
    `${GHPATH}/img/theme.png`,
    `${GHPATH}/img/town.png`,
    `${GHPATH}/img/woods.png`
];

var CACHE_NAME = APP_PREFIX + VERSION;
self.addEventListener("fetch", function (e) {
    console.log("Fetch request : " + e.request.url);
    e.respondWith(
        caches.match(e.request).then(function (request) {
            if (request) {
                console.log("Responding with cache : " + e.request.url);
                return request;
            } else {
                console.log("File is not cached, fetching : " + e.request.url);
                return fetch(e.request);
            }
        })
    );
});

self.addEventListener("install", function (e) {
    e.waitUntil(
        caches.open(CACHE_NAME).then(function (cache) {
            console.log("Installing cache : " + CACHE_NAME);
            return cache.addAll(URLS);
        })
    );
});

self.addEventListener("activate", function (e) {
    e.waitUntil(
        caches.keys().then(function (keyList) {
            var cacheWhitelist = keyList.filter(function (key) {
                return key.indexOf(APP_PREFIX);
            });
            cacheWhitelist.push(CACHE_NAME);
            return Promise.all(
                keyList.map(function (key, i) {
                    if (cacheWhitelist.indexOf(key) === -1) {
                        console.log("Deleting cache : " + keyList[i]);
                        return caches.delete(keyList[i]);
                    }
                })
            );
        })
    );
});