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GoogleChrome/sw-toolbox: A collection of tools for service workers.

Service Worker Toolbox

A collection of tools for service workers

Service Worker Toolbox provides some simple helpers for use in creating your own service workers. Specifically, it provides common caching patterns and anexpressive approachto using those strategies for runtime requests. If you’re not sure what service workers are or what they are for, start withthe explainer doc.

Install

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

Register your service worker

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

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

As implemented in Chrome 40 or later, 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.

For even lower friction you can instead include the Service Worker Toolbox companion script in your HTML as shown below. Be aware that this is not customizable. If you need to do anything fancier than registering with a default scope, you’ll need to use the standard registration.

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

Add Service Worker Toolbox to your service 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

Usage

Basic Routes

A route is a URL pattern and request method associated with a handler. It defines the behaviour for a section of the site. Routing is the process of matching an incoming request with the most appropriate route. To define a route you call the appropriate method on toolbox.router .

For example, to send GET requests for the URL '/myapp/index.html' to the built-in toolbox.networkFirst handler, you would write the following in your service worker file:

toolbox.router.get(‘/myapp/index.html’, toolbox.networkFirst);

If you don’t need wildcards in your route, and your route applies to the same domain as your main site, then you can use a string like '/myapp/index.html' . However, if you need wildcards (e.g. match any URL that begins with /myapp/ ), or if you need to match URLs that belong to different domains (e.g. match https://othersite.com/api/ ), sw-toolbox has two options for configuring your routes.

Express-style Routes

For developers familiar with Express routing , sw-toolbox offers support for similar named wildcards, via the path-to-regexp library.

If you use a String to define your route, it’s assumed you’re using Express-style routes.

By default, a route will only match URLs on the same origin as the service worker. If you’d like your Express-style routes to match URLs on different origins, you need to pass in a value for the origin option. The value could be either a String (which is checked for an exact match) or a RegExp object. In both cases, it’s matched against the full origin of the URL (e.g. 'https://example.com' ).

Some examples of using Express-style routing include:

// URL patterns are the same syntax as Express 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'});

Regular Expression Routes

Developers who are more comfortable using regular expressions can use an alternative syntax to define routes, passing in a RegExp object as the first parameter. This RegExp will be matched against the full request URL when determining whether the route applies, including the origin and path. This can lead to simpler cross-origin routing vs. Express-style routes, since both the origin and the path are matched simultaneously, without having to specify a separate origin option.

Note that while Express-style routes allow you to name path fragment parameters that will be passed to your handler (see values.foo in the previous example), that functionality is not supported while using regular expression routes.

Some examples of using Regular Expression routing include:

// Match URLs that end in index.html toolbox.router.get(/index.html$/, function(request) {   return new Response('Handled a request for ' + request.url); });  // Match URLs that begin with https://api.example.com toolbox.router.post(/^https:////api.example.com///, apiHandler);

The Default Route

sw-toolbox supports defining an optional "default" route via toolbox.router.default that is used whenever there is no alternative route for a given URL. If toolbox.router.default is not set, then sw-toolbox will just ignore requests for URLs that don’t match any alternative routes, and the requests will potentially be handled by the browser as if there were no service worker involvement.

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

Precaching

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']);

Defining Request Handlers

A request handler takes three arguments.

var myHandler = function(request, values, options) {   // ... }
  • request – The Request object that triggered the fetch event
  • values – When using Express-style routing paths, this will be an 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'} . When using a RegExp for the path, values will not be set.
  • options – theoptionspassed to one of therouter methods.

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.

API

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 toolbox.router 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. 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 the Cache used to store Response objects. 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]

Imposes 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]

Imposes 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

Built-in handlers

There are five 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. It’s 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. This option is good for resources that don’t change, or 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. This option is good for when you need to guarantee that no network request will be made, for example saving battery on mobile.

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.

Methods

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 thepath-to-regexp module for the full syntax
  • handler – a request handler, asdescribed above
  • options – an object containing options for the route. This options object will be passed to the request handler. The origin option is specific to the router methods, and can be either 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

Takes a function to use 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 and returns a Promise that resolves with void. The options parameter supports the debug and cache global options.

toolbox.uncache(url, options)

Causes the resource at url to be removed from the cache and returns a Promise that resolves to true if the cache entry is deleted. The options parameter supports the debug and cache global options.

Support

If you’ve found an error in this library, please file an issue at: 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.

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