skipWaiting in message handler doesn't work

[zdila]

Library Affected:
workbox-core

Browser & Platform:
"all browsers"

Issue or Feature Request Description:

Calling skipWaiting() in message event handler does nothing. Instead calling self.skipWaiting() works. Tested in latest stable Chrome and Firefox.

Application uses webpack an InjectManifest plugin.

import { skipWaiting } from 'workbox-core';

addEventListener('message', (event) => {
  if (event.data && event.data.type === 'SKIP_WAITING') {
   // skipWaiting(); // does nothing
    self.skipWaiting(); // works
  }
});

// ...

[jeffposnick]

The skipWaiting function in workbox-core wraps the call to self.skipWaiting() inside of an install event handler:

workbox/packages/workbox-core/src/skipWaiting.ts

Lines 22 to 26 in 8ffe560

	function skipWaiting() {
	// We need to explicitly call `self.skipWaiting()` here because we're
	// shadowing `skipWaiting` with this local function.
	self.addEventListener('install', () => self.skipWaiting());
	}

I have wondered how much value is added by workbox-core's skipWaiting(), since it should be "safe" to call self.skipWaiting() outside of an install handler. (The same isn't the case for self.clients.claim(), which throws an exception when called unless there's an active service worker.)

I'm in favor making a change in v6 that just makes workbox-core's skipWaiting() call self.skipWaiting() directly, without the install event wrapper, and logs a message in dev mode telling folks to migrate to using self.skipWaiting() directly. And then maybe we'll remove skipWaiting() in v7.