service-worker.ts

/// <reference lib="webworker" />
/* eslint-disable no-restricted-globals */

import { clientsClaim } from 'workbox-core';
import { ExpirationPlugin } from 'workbox-expiration';
import { precacheAndRoute, createHandlerBoundToURL } from 'workbox-precaching';
import { registerRoute } from 'workbox-routing';
import { StaleWhileRevalidate } from 'workbox-strategies';

declare const self: ServiceWorkerGlobalScope;

clientsClaim();

// Precache all of the assets generated by the build process.
// Their URLs are injected into the manifest variable below.
// This variable must be present somewhere in the service worker file,
// even if you decide not to use precaching.
precacheAndRoute(self.__WB_MANIFEST);

// Set up App Shell-style routing, so that all navigation requests
// are fulfilled with the index.html shell.
const fileExtensionRegexp = new RegExp('/[^/?]+\\.[^/]+$');
registerRoute(
    // Return false to exempt requests from being fulfilled by index.html.
    ({request, url}: {request: Request; url: URL}) => {
        // If this isn't a navigation, skip.
        if (request.mode !== 'navigate') {
            return false;
        }

        // If this is a URL that starts with /_, skip.
        if (url.pathname.startsWith('/_')) {
            return false;
        }

        // If this looks like a URL for a resource, because it contains
        // a file extension, skip.
        if (url.pathname.match(fileExtensionRegexp)) {
            return false;
        }

        // Return true to signal that we want to use the handler.
        return true;
    },
    createHandlerBoundToURL(process.env.PUBLIC_URL + '/index.html')
);

// Runtime caching route for images requests that aren't handled by the precache.
registerRoute(
    // Add in any other file extensions or routing criteria as needed.
    ({url}) => url.origin === self.location.origin && url.pathname.match(/.(png|jpg|jpeg|gif)$/),
    // Customize this strategy as needed, e.g., by changing to CacheFirst.
    new StaleWhileRevalidate({
        cacheName: 'images',
        plugins: [
            // Ensure that once this runtime cache reaches a maximum size the
            // least-recently used images are removed.
            new ExpirationPlugin({maxEntries: 50}),
        ],
    })
);

// This allows the web app to trigger skipWaiting via
// registration.waiting.postMessage({type: 'SKIP_WAITING'})
self.addEventListener('message', (event) => {
    if (event.data && event.data.type === 'SKIP_WAITING') {
        self.skipWaiting();
    }
});