Service Worker lifecycle traps

Summary

New SW waits in waiting until tabs close — users stuck on old cache. skipWaiting + clients.claim() forces update but can mid-session break. Version caches explicitly; delete old caches on activate. Scope limited to path — wrong registration path = no control. Auth tokens in SW cache = risk.

Code example

self.addEventListener('install', (event) => {
  self.skipWaiting();
});

self.addEventListener('activate', (event) => {
  event.waitUntil(
    caches.keys().then((keys) =>
      Promise.all(keys.filter((k) => k !== CACHE_VERSION).map((k) => caches.delete(k)))
    )
  );
  clients.claim();
});

Key points

• New SW waits in waiting until tabs close — users stuck on old cache.
• skipWaiting + clients.claim() forces update but can mid-session break.
• Version caches explicitly; delete old caches on activate.
• Scope limited to path — wrong registration path = no control.
• Auth tokens in SW cache = risk.

Further reading

• Service worker lifecycle
• Service worker caching

Related concepts

• Same-origin policy nuances
• SharedArrayBuffer