Asset Manager

A simple build tool for managing your Service Worker resource cache.

Install

npm i -S @codewithkyle/asset-manager

Usage

package.json

{
    "scripts": {
        "wrangle": "asset-manager"
    }
}

asset-manager.config.js

Note that the publicDir value should be a path relative to your projects root web directory and it should be accessible to the Service Worker (within it's scope).

module.exports = {
    src: [
        {
            files: "./public/js/*.js",
            publicDir: "/js",
        },
        {
            files: "./public/css/*.css",
            publicDir: "/css",
        },
    ],
    output: "./public/service-worker-assets.js",
    static: ["/", "/404"],
};

Example Service Worker

<script type="module">
    if (
        location.origin.indexOf("localhost") === -1 &&
        "serviceWorker" in navigator
    ) {
        navigator.serviceWorker.register("/service-worker.js", { scope: "/" });
        navigator.serviceWorker.ready.then(async (registration) => {
            await import("/service-worker-assets.js?t=" + Date.now());
            if (self.manifest.version !== localStorage.getItem("version")) {
                registration.active.postMessage(self.manifest);
                localStorage.setItem("version", self.manifest.version);
            }
        });
    }
</script>

self.addEventListener("install", (event) => event.waitUntil(onInstall(event)));
self.addEventListener("activate", (event) =>
    event.waitUntil(onActivate(event))
);
self.addEventListener("fetch", (event) => event.respondWith(onFetch(event)));

self.importScripts("./service-worker-assets.js?t=" + Date.now());
let cacheNamePrefix = "resource-cache";
let cacheName = `${cacheNamePrefix}-${self.manifest.version}`;

// Cache files when the service worker is installed or updated
async function onInstall(event) {
    self.skipWaiting();
    console.log("SW Installed");
}

// Cleanup old caches
async function onActivate(event) {
    console.log("SW Activated");
}

// Try to respond with cached files
async function onFetch(event) {
    // Remove navigate if you're not building an SPA
    if (event.request.mode === "navigate") {
        const cache = await caches.open(cacheName);
        const cachedResponse = await cache.match("index.html");
        return cachedResponse;
    } else if (
        event.request.method === "GET" &&
        event.request.url.indexOf(self.origin) === 0
    ) {
        const cache = await caches.open(cacheName);
        const cachedResponse = await cache.match(event.request);
        if (cachedResponse) {
            return cachedResponse;
        }
    }
    return fetch(event.request);
}

self.addEventListener("message", async (event) => {
    cacheName = `${cacheNamePrefix}-${event.data.version}`;
    const assetsRequests = self.manifest.assets.map((asset) => {
        return new Request(asset, {
            cache: "reload",
        });
    });
    for (const request of assetsRequests) {
        await caches
            .open(cacheName)
            .then((cache) => cache.add(request))
            .catch((error) => {
                console.error("Failed to cache:", request, error);
            });
    }
    const cacheKeys = await caches.keys();
    await Promise.all(
        cacheKeys
            .filter(
                (key) => key.startsWith(cacheNamePrefix) && key !== cacheName
            )
            .map((key) => caches.delete(key))
    );
});