sw-toolbox

Service Worker Toolbox

A collection of tools for service workers

Service Worker helpers

Service Worker Toolbox provides some simple helpers for use in creating your own service workers. If you're not sure what service workers are or what they are for, start with the explainer doc.

Installing Service Worker Toolbox

Service Worker Toolbox is available through Bower, npm or direct from github:

bower install --save sw-toolbox

npm install --save sw-toolbox

git clone https://github.com/GoogleChrome/sw-toolbox.git

Registering your service worker

From your registering page, register your service worker in the normal way. For example:

navigator.serviceWorker.register('my-service-worker.js');

For even lower friction, if you don't intend to doing anything more fancy than just registering with a default scope, you can instead include the Service Worker Toolbox companion script in your HTML:

<script src="/path/to/sw-toolbox/companion.js" data-service-worker="my-service-worker.js"></script>

As currently implemented in Chrome 40+, a service worker must exist at the root of the scope that you intend it to control, or higher. So if you want all of the pages under /myapp/ to be controlled by the worker, the worker script itself must be served from either / or /myapp/. The default scope is the containing path of the service worker script.

Using Service Worker Toolbox in your worker script

In your service worker you just need to use importScripts to load Service Worker Toolbox

importScripts('bower_components/sw-toolbox/sw-toolbox.js'); // Update path to match your own setup

Basic usage

Within your service worker file

// Set up routes from URL patterns to request handlers
toolbox.router.get('/myapp/index.html', someHandler);

// For some common cases Service Worker Toolbox provides a built-in handler
toolbox.router.get('/', toolbox.networkFirst);

// URL patterns are the same syntax as ExpressJS routes
// (http://expressjs.com/guide/routing.html)
toolbox.router.get(':foo/index.html', function(request, values) {
  return new Response('Handled a request for ' + request.url +
      ', where foo is "' + values.foo + '"');
});

// For requests to other origins, specify the origin as an option
toolbox.router.post('/(.*)', apiHandler, {origin: 'https://api.example.com'});

// Provide a default handler for GET requests
toolbox.router.default = myDefaultRequestHandler;

// You can provide a list of resources which will be cached at service worker install time
toolbox.precache(['/index.html', '/site.css', '/images/logo.png']);

Request handlers

A request handler receives three arguments

var myHandler = function(request, values, options) {
  // ...
}

• request - Request object that triggered the fetch event
• values - Object whose keys are the placeholder names in the URL pattern, with the values being the corresponding part of the request URL. For example, with a URL pattern of '/images/:size/:name.jpg' and an actual URL of '/images/large/unicorns.jpg', values would be {size: 'large', name: 'unicorns'}
• options - the options object that was used when creating the route

The return value should be a Response, or a Promise that resolves with a Response. If another value is returned, or if the returned Promise is rejected, the Request will fail which will appear to be a NetworkError to the page that made the request.

Built-in handlers

There are 5 built-in handlers to cover the most common network strategies. For more information about offline strategies see the Offline Cookbook.

toolbox.networkFirst

Try to handle the request by fetching from the network. If it succeeds, store the response in the cache. Otherwise, try to fulfill the request from the cache. This is the strategy to use for basic read-through caching. Also good for API requests where you always want the freshest data when it is available but would rather have stale data than no data.

toolbox.cacheFirst

If the request matches a cache entry, respond with that. Otherwise try to fetch the resource from the network. If the network request succeeds, update the cache. Good for resources that don't change, or for which you have some other update mechanism.

toolbox.fastest

Request the resource from both the cache and the network in parallel. Respond with whichever returns first. Usually this will be the cached version, if there is one. On the one hand this strategy will always make a network request, even if the resource is cached. On the other hand, if/when the network request completes the cache is updated, so that future cache reads will be more up-to-date.

toolbox.cacheOnly

Resolve the request from the cache, or fail. Good for when you need to guarantee that no network request will be made - to save battery on mobile, for example.

toolbox.networkOnly

Handle the request by trying to fetch the URL from the network. If the fetch fails, fail the request. Essentially the same as not creating a route for the URL at all.

API

Global Options

All options can be specified globally via properties of toolbox.options. Any individual options can be configured on a per-handler basis, via the Object passed as the third parameter to the toolbox.router.get(urlPattern, handler, options), etc. methods.

debug [Boolean]

Determines whether extra information is logged to the browser's console. Default: false

networkTimeoutSeconds [Number]

A timeout that applies to the toolbox.networkFirst built-in handler. If networkTimeoutSeconds is set, then any network requests that take longer than that amount of time will automatically fall back to the cached response if one exists. By default, when networkTimeoutSeconds is not set, the browser's native networking timeout logic applies. Default: null

cache [Object]

Various properties of cache control the behavior of the default cache when set via toolbox.options.cache, or the cache used by a specific request handler.

cache.name [String]

The name of Cache used to store Responses. Using a unique name allows you to customize the cache's maximum size and age of entries. Default: Generated at runtime based on the service worker's registration.scope value.

cache.maxEntries [Number]

The cache.maxEntries option can be used to impose a least-recently used cache expiration policy on entries cached via the various built-in handlers. You can use this with a cache that's dedicated to storing entries for a dynamic set of resources with no natural limit. Setting cache.maxEntries to, e.g., 10 would mean that after the 11th entry is cached, the least-recently used entry would be automatically deleted. The cache should never end up growing beyond cache.maxEntries entries. This option will only take effect if cache.name is also set. It can be used alone or in conjunction with cache.maxAgeSeconds. Default: null

cache.maxAgeSeconds [Number]

The maxAgeSeconds option can be used to impose a maximum age for cache entries, in seconds. You can use this with a cache that's dedicated to storing entries for a dynamic set of resources with no natural limit. Setting cache.maxAgeSeconds to, e.g., 60 * 60 * 24 would mean that any entries older than a day would automatically be deleted. This option will only take effect if cache.name is also set. It can be used alone or in conjunction with cache.maxEntries. Default: null

toolbox.router.get(urlPattern, handler, options)

toolbox.router.post(urlPattern, handler, options)

toolbox.router.put(urlPattern, handler, options)

toolbox.router.delete(urlPattern, handler, options)

toolbox.router.head(urlPattern, handler, options)

Create a route that causes requests for URLs matching urlPattern to be resolved by calling handler. Matches requests using the GET, POST, PUT, DELETE or HEAD HTTP methods respectively.

• urlPattern - an Express style route. See the docs for the path-to-regexp module for the full syntax
• handler - a request handler, as described above
• options - an object containing options for the route. This options object will be available to the request handler. The origin option is specific to the route methods, and is an exact string or a Regexp against which the origin of the Request must match for the route to be used.

toolbox.router.any(urlPattern, handler, options)

Like toolbox.router.get, etc., but matches any HTTP method.

toolbox.router.default

If you set this property to a function it will be used as the request handler for any GET request that does not match a route.

toolbox.precache(arrayOfURLs)

Add each URL in arrayOfURLs to the list of resources that should be cached during the service worker install step. Note that this needs to be called before the install event is triggered, so you should do it on the first run of your script.

toolbox.cache(url, options)

Causes the resource at url to be added to the cache. Returns a Promise. Supports the debug and cache global options.

toolbox.uncache(url, options)

Causes the resource at url to be removed from the cache. Returns a Promise. Supports the debug and cache global options.

Support

If you’ve found an error in this library, please file an issue: https://github.com/GoogleChrome/sw-toolbox/issues

Patches are encouraged, and may be submitted by forking this project and submitting a pull request through GitHub.

License

Copyright 2015 Google, Inc.

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.