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Migrate from Workbox v5 to v6

This guide is focused on breaking changes introduced in Workbox v6, with examples of what changes you'd need to make when upgrading from Workbox v5.

Breaking Changes

workbox-core

The skipWaiting() method in workbox-core will no longer add in an install handler and is equivalent to just calling self.skipWaiting().

From now on, use self.skipWaiting() instead since skipWaiting() will likely be removed in Workbox v7.

workbox-precaching

  • Cross-origin HTML documents for URLs that correspond to an HTTP redirect can no longer be used to satisfy a navigation request with workbox-precaching. This scenario is generally uncommon.

  • The fbclid URL query parameter is now ignored by workbox-precaching when looking up a precached response for a given request.

workbox-routing

The setDefaultHandler() method now takes an optional second parameter corresponding to the HTTP method that it applies to, defaulting to 'GET'.

  • If you use setDefaultHandler() and all your requests are GET, then no changes need to be made.

  • If you have any requests that are not GET (POST, PUT, etc...), setDefaultHandler() will no longer cause those requests to match.

Build Configuration

The mode option for the getManifest and injectManifest modes in workbox-build and workbox-cli was not intended to be supported and has been removed. This does not apply to workbox-webpack-plugin, which does support mode in its InjectManifest plugin.

Build Tools Require Node.js v10 or Higher

Node.js versions prior to v10 are no longer supported for workbox-webpack-plugin, workbox-build, or workbox-cli. Please update your Node.js runtime to a supported version.

New Improvements

workbox-strategies

Workbox v6 introduces a new way for third-party developers to define their own Workbox strategies. This ensures third-party developers have the capability to extend Workbox in ways that fully meet their needs.

New Strategy base class

In v6, all Workbox strategy classes must extend the new Strategy base class. All of the built-in strategies have been rewritten to support this.

The Strategy base class is responsible for two primary things:

  • Invoking plugin lifecycle callbacks common to all strategy handlers (e.g. when they start, respond, and end).
  • Creating a "handler" instance, that can manage state for each individual request a strategy is handling.

New "handler" class

We previously had internal modules call fetchWrapper and cacheWrapper, which (as their name implies) wrap the various fetch and cache APIs with hooks into their lifecycle. This is the mechanism that currently allows plugins to work, but it's not exposed to developers.

The new "handler" class, StrategyHandler, will expose these methods so custom strategies can call fetch() or cacheMatch() and have any plugins that were added to the strategy instance automatically invoked.

This class would also make it possible for developers to add their own custom, lifecycle callbacks that might be specific to their strategies, and they would "just work" with the existing plugin interface.

New plugin lifecycle state

In Workbox v5, plugins are stateless. That means if a request for /index.html triggers both the requestWillFetch and cachedResponseWillBeUsed callbacks, those two callbacks have no way of communicating with each other or even knowing that they were triggered by the same request.

In v6, all plugin callbacks will also be passed a new state object. This state object will be unique to this particular plugin object and this particular strategy invocation (i.e. the call to handle()). This allows developers to write plugins where one callback can conditionally do something based on what another callback in the same plugin did (e.g. compute the time delta between running requestWillFetch and fetchDidSucceed or fetchDidFail).

New plugin lifecycle callbacks

New plugin lifecycle callbacks have been added to allow developers to fully leverage the plugin lifecycle state:

  • handlerWillStart: called before any handler logic starts running. This callback can be used to set the initial handler state (e.g. record the start time).
  • handlerWillRespond: called before the strategies handle() method returns a response. This callback can be used to modify that response before returning it to a route handler or other custom logic.
  • handlerDidRespond: called after the strategy's handle() method returns a response. This callback can be used to record any final response details, e.g. after changes made by other plugins.
  • handlerDidComplete: called after all extend lifetime promises added to the event from the invocation of this strategy have settled. This callback can be used to report on any data that needs to wait until the handler is done in order to calculate (e.g. cache hit status, cache latency, network latency).
  • handlerDidError: called if the handler was unable to provide a valid response from any source. This callback can be used to provide "fallback" content as an alternative to a network error.

Developers implementing their own custom strategies do not have to worry about invoking these callbacks themselves; that's all handled by a new Strategy base class.

More accurate TypeScript types for handlers

TypeScript definitions for various callback methods have been normalized. This should lead to a better experience for developers who use TypeScript and write their own code to implement or call handlers.

workbox-window

New messageSkipWaiting() method

A new method, messageSkipWaiting(), has been added to the workbox-window module to simplify the process of telling the "waiting" service worker to activate. This offers some improvements:

  • It calls postMessage() with the de facto standard message body, {type: 'SKIP_WAITING'}, that a service worker generated by Workbox checks for to trigger skipWaiting().

  • It chooses the correct "waiting" service worker to post this message to, even if it's not the same service worker that workbox-window was registered with.

Removal of "external" events in favor of an isExternal property

All "external" events in workbox-window have been removed in place of "normal" events with an isExternal property set to true. This allows developers who care about the distinction to still detect it, and developers who don't need to know can ignore the property.

Cleaner "Offer a page reload for users" recipe

Thanks to both of the above changes, the "Offer a page reload for users" recipe can be simplified:

// v6:
<script type="module">
import {Workbox} from 'https://storage.googleapis.com/workbox-cdn/releases/6.0.0-alpha.1/workbox-window.prod.mjs';

if ('serviceWorker' in navigator) {
  const wb = new Workbox('/sw.js');

  const showSkipWaitingPrompt = () => {
    // This assumes a hypothetical createUIPrompt() method with
    // onAccept and onReject callbacks:
    const prompt = createUIPrompt({
      onAccept: () => {
        wb.addEventListener('controlling', () => {
          window.location.reload();
        });

        // This will postMessage() to the waiting service worker.
        wb.messageSkipWaiting();
      },

      onReject: () => {
        prompt.dismiss();
      }
    });
  };

  // Listening for externalwaiting is no longer needed.
  wb.addEventListener('waiting', showSkipWaitingPrompt);
  wb.register();
}
</script>

workbox-routing

A new boolean parameter, sameOrigin, is passed to the matchCallback function used in workbox-routing. It's set to true if the request is for a same-origin URL, and false otherwise.

This simplifies some common boilerplate:

// In v5:
registerRoute(
  ({url}) => url.origin === self.location.origin &&
             url.pathname.endsWith('.png'),
  new StaleWhileRevalidate({cacheName: 'local-png'}),
);

// In v6:
registerRoute(
  ({sameOrigin, url}) => sameOrigin &&
                         url.pathname.endsWith('.png'),
  new StaleWhileRevalidate({cacheName: 'local-png'}),
);

matchOptions in workbox-expiration

You can now set matchOptions in workbox-expiration, which will then be passed through as the CacheQueryOptions to the underlying cache.delete() call. (Most developers won't need to do this.)

workbox-precaching

Uses workbox-strategies

workbox-precaching has been rewritten to use workbox-strategies as a base. This should not result in any breaking changes, and should lead to better long-term consistency in how the two modules access the network and cache.

Precaching now processes entries one by one, not in bulk

workbox-precaching has been updated so that only one entry in the precache manifest is requested and cached at a time, instead of attempting to request and cache all of them at once (leaving it to the browser to figure out how to throttle).

This should reduce the likelihood of net::ERR_INSUFFICIENT_RESOURCES errors while precaching, and also should reduce the bandwidth contention between precaching and simultaneous requests made by the web app.

PrecacheFallbackPlugin allows for easier offline fallback

workbox-precaching now includes a PrecacheFallbackPlugin, which implements the new handlerDidError lifecycle method added in v6.

This makes it easy to specify a precached URL as a "fallback" for a given strategy when a response otherwise wouldn't be available. The plugin will take care of properly constructing the correct cache key for the precached URL, including any revision parameter that's needed.

Here's a sample of using it to respond with a precached /offline.html when the NetworkOnly strategy can't generate a response for a navigation request—in other words, displaying a custom offline HTML page:

import {PrecacheFallbackPlugin, precacheAndRoute} from 'workbox-precaching';
import {registerRoute} from 'workbox-routing';
import {NetworkOnly} from 'workbox-strategies';

// Ensure that /offline.html is part of your precache manifest!
precacheAndRoute(self.__WB_MANIFEST);

registerRoute(
  ({request}) => request.mode === 'navigate',
  new NetworkOnly({
    plugins: [
      new PrecacheFallbackPlugin({
        fallbackURL: '/offline.html',
      }),
    ],
  }),
);

precacheFallback in runtime caching

If you're using generateSW to create a service worker for you instead of writing your service worker by hand, you can use the new precacheFallback configuration option in runtimeCaching to accomplish the same thing:

{
  // ... other generateSW config options...
  runtimeCaching: [{
    urlPattern: ({request}) => request.mode === 'navigate',
    handler: 'NetworkOnly',
    options: {
      precacheFallback: {
        // This URL needs to be included in your precache manifest.
        fallbackURL: '/offline.html',
      },
    },
  }],
}

Getting Help

We anticipate most migrations to be straightforward. If you run into issues not covered in this guide, please let us know by opening an issue on GitHub.