v149 · Performance · demo

Router Timing Inspector

Registers a service worker with Static Routing rules, fires fetch requests through each route type, then reads workerMatchedRouterSourceList and workerFinalRouterSourceList from the timing entries.

⟳ Checking support…
Service worker: not registered
Results will appear after running the test.
// New in Chrome 149 — PerformanceResourceTiming fields:
// workerMatchedRouterSourceList — source declared in the matching rule
// workerFinalRouterSourceList   — actual source used (may differ on cache miss)

const observer = new PerformanceObserver(list => {
  for (const entry of list.getEntries()) {
    if (entry.entryType !== 'resource') continue;
    console.log(entry.name);
    console.log('matched:', entry.workerMatchedRouterSourceList); // e.g. ['cache']
    console.log('final:  ', entry.workerFinalRouterSourceList);   // e.g. ['network'] on cache miss
  }
});
observer.observe({ type: 'resource', buffered: true });

see also