Use a single fetch handler for all Router instances

Library Affected: 5.0.0 workbox-google-analytics, workbox-routing, etc.

Browser & Platform: “all browsers”

Issue or Feature Request Description:

I’m using setDefaultHandler with offline-fallback page “sw-offline” to handle non-matching requests along with offline googleAnalytics.

However, the fetch routes added by googleAnalytics is not preferred over setDefaultHandler. For all “google analytics” requests, default route set by setDefaultHandler is used.

	// few registerRoute are used here

	workbox.googleAnalytics.initialize(); 
	const defaultNetworkOnlyHandler = async (args) => {
		console.log('Default:'+args.url);
		try {
			var defaultNetworkOnly = new NetworkOnly({
				fetchOptions: args.event.request.mode=='navigate'?{}:{credentials:'include'}
			});
			const response = await defaultNetworkOnly.handle(args);
			return response || await caches.match('sw-offline');
		} catch(error) {
			return await caches.match('sw-offline');
		}
	};
	setDefaultHandler(defaultNetworkOnlyHandler);

As it can be seen in console, “https://www.google-analytics.com/analytics.js” always uses default route of “NetworkOnly” instead of “NetworkFirst” route defined in workbox-google-analytics. Due to which analytics.js is not cached and throws an error in offline mode.

[jeffposnick]

Actually, I forgot that workbox-precaching in v6 creates it own Router instead of using the default Router, so forget what I said about it being similar.

[nhoizey]

@jeffposnick ok, thanks!