ReportingObserver: know your code health
ReportingObserver gives developers insight into what their code is doing in the wild. ReportingObserver surfaces information on issues like deprecations and interventions, messages that were previously only available in the DevTools console.
Offline Google Analytics Made Easy
The sw-offline-google-analytics library gives you everything you need.
Send beacon data in Chrome 39
Chrome 39 implements the Beacon API, which allows to send small async HTTP requests during the page unload events.