Create React App PWA - change caching strategy of service worker - reactjs

Question

I have created a PWA template using CRA v4 and enabled the service worker that comes with it by registering it, because I needed to create a pop up notification about installing the PWA.
The lighthouse test has to pass for the app to be PWA compatible so that the browser would fire the beforeinstallprompt event listener needed to detect if the user has already installed the PWA or not.
The problem now is that this service worker is using cache-first strategy. As a result refreshing the page does not trigger an update and I am left with an older version of the app appearing after I have deployed an update.
How can I change the caching strategy of CRA v4's service worker such that the user would get a new version of the app by simply refreshing the page?
I am also interested in knowing why this cache-first strategy is used by default. To me it seems bad that the user has to close every tab to get a new version. Why haven't more people brought this up? This is clearly not user friendly...

Answer 1

To change the strategy you need to implement your own code changing service-worker.js and potentially
serviceWorkerRegistration.js. (https://developers.google.com/web/tools/workbox/modules/workbox-strategies)
I implement my own strategy:
check for updates at the very beginning check for updates each 3 min if there is a update in the very beginning update
cache and refresh the website. if it is after show a popup asking to fresh
serviceWorkerRegistration.ts
/**
* ...... previous code
**/
const CHECK_INTERVAL_TIME = 1000 * 60 * 3 // 3 min
function registerValidSW(swUrl: string, config?: Config) {
navigator.serviceWorker
.register(swUrl)
.then((registration) => {
registration.onupdatefound = () => {
const installingWorker = registration.installing;
if (installingWorker == null) {
return;
}
installingWorker.onstatechange = () => {
if (installingWorker.state === 'installed') {
if (navigator.serviceWorker.controller) {
// At this point, the updated precached content has been fetched,
// but the previous service worker will still serve the older
// content until all client tabs are closed.
console.log(
'New content is available and will be used when all ' +
'tabs for this page are closed. See https://cra.link/PWA.'
);
// Execute callback
if (config && config.onUpdate) {
config.onUpdate(registration);
}
} else {
// At this point, everything has been precached.
// It's the perfect time to display a
// "Content is cached for offline use." message.
console.info('Content is cached for offline use.');
// Execute callback
if (config && config.onSuccess) {
config.onSuccess(registration);
}
}
}
};
};
/****************************
start new code
*****************************/
registration.update().then(() => console.debug("Checked for update...")).catch(console.error)
setInterval(() => {
console.debug("Checked for update...");
registration.update().catch(console.error);
}, CHECK_INTERVAL_TIME);
/****************************
end new code
*****************************/
})
.catch((error) => {
console.error('Error during service worker registration:', error);
});
}
App.tsx
/**
* ...... previous code
**/
function App() {
const time = useRef(Date.now()); //can be let, depending of your logic
useEffect(() => {
serviceWorkerRegistration.register({
onSuccess(registration) {
console.debug('serviceWorkerRegistration success')
},
onUpdate(registration) {
console.debug('serviceWorkerRegistration updated',Date.now()-time.current)
const refresh=async ()=>{
await registration?.waiting.postMessage({type: 'SKIP_WAITING'}); //send message to update the code (stop waiting)
if ('caches' in window) { //delete cache, i think is no necessary but you lose nothing
const names = await caches.keys()
for (const name of names) {
await caches.delete(name)
}
}
window.location.reload();
}
if (Date.now()-time.current<=2000){
return refresh()
}
logicToShowPopup({
onClick: refresh
})
}
})
}, [])
return (<div>My App</div>)
}
I hope this suits for your needs