There isn't a way to get "all the browser's" registered service workers programmatically from a web page, since a web page can only access the service workers that are registered for its scope. But if you're looking for a way to get those, then call navigator.serviceWorker.getRegistrations to get a promise that resolves to an array of registered service workers:

navigator.serviceWorker.getRegistrations().then(function(registrations) {  registrations.forEach(function(v) { console.log('service worker: ' + v) });});

Apparently I have found two ways that works fine for me (for chrome):one is using shortcut command:

chrome://serviceworker-internals/

Other one is:

go to Developers Tool -> Resources -> Service Workers

If you really want to get "all the browser's" registered service workers, you can do it non-programmatically by opening these URLs:

Firefox

about:serviceworkers

Chrome

chrome://serviceworker-internals/

Opera

browser://serviceworker-internals

See also: Is ServiceWorker Ready? for an up-to-date list of debugging helpers.

(Presumably there's also a way to do this programmatically in a Firefox extension.)