:v: Proxy fetch requests through the Background Sync API
Proxy fetch requests through the Background Sync API
Made with ❤ at @outlandish
Fetch Sync allows you to proxy fetch requests through the Background Sync API so that they are honoured if made when the UA is offline! Hooray!
Check out a live demo here.
fetchSync.{get,getAll,cancel,cancelAll}().
importScripts, or handles SW registration for you.
fetchrequests.
npm install fetch-sync --save
The library utilises some new technologies so currently only works in some browsers. It definitely works in Chrome Canary with the
experimental-web-platform-featuresflag enabled.
The browser must support:
Chrome Canary |
Chrome | Firefox | IE | Opera | Safari |
---|---|---|---|---|---|
✔ | ✔ | ✘ | ✘ | ✘ | ✘ |
Client
// ES6 import fetchSync from 'fetch-sync'
// CommonJS var fetchSync = require('fetch-sync')
Worker
See Initialise for details on importing and registering the service worker.
Existing Service Worker
If your application already uses a Service Worker, you can import the fetch-sync worker using
importScripts:
importScripts('node_modules/fetch-sync/dist/fetch-sync.sw.min.js')
And then call
fetchSync.init()somewhere in your application's initialisation procedure.
No Service Worker
fetch-sync can handle registration if you don't use a SW already...
Either serve the fetch-sync worker file with a header
"Service-Worker-Allowed : /", or to avoid configuring headers, create a Service Worker script in the root of your project and use the method above for 'Existing Service Worker'.
Then see the example under Usage for the
fetchSync.init()method.
fetchSync.init([options]) : Promise
Initialise fetchSync.
sw-registeravailable options and for more details on Service Worker registration.
Example:
// Import client lib...// ES6 import fetchSync from 'fetch-sync'
// ES5 var fetchSync = require('fetch-sync')
// Initialise, passing in worker lib location...fetchSync.init({ url: 'node_modules/fetch-sync/dist/fetch-sync.sw.js', scope: '' // e.g. 'http://localhost:8000' })
fetchSync([name, ]request[, options]) : Sync
syncBackground Sync operation.
Returns a Promise that resolves on success of the fetch request. Rejects if a sync exists with this name already.
There are also some properties/methods on the Promise. See the Sync API for more details.
If called with a
name:
fetchSync.get('name').then(sync => sync.response).
sync.remove().
Examples:
named GET
fetchSync('GetMessages', '/messages') .then((response) => response.json()) .then((json) => console.log(json.foo))
unnamed POST
const post = fetchSync('/update-profile', { method: 'POST', body: { name: '' } })// cancel the sync... post.cancel()
unnamed with options
const headers = new Headers();headers.append('Authorization', 'Basic abcdefghijklmnopqrstuvwxyz');
//
fetchSync
accepts the same args asfetch
... fetchSync('/send-message', { headers })
named with options
fetchSync('/get-messages', { headers })
unnamed with Request
fetchSync( new Request('/messages') )
fetchSync.get(name) : Sync
Get a sync by its name.
Returns a Promise that resolves with success of the sync operation or reject if sync operation is not found.
There are also some properties/methods on the Promise. See the Sync API for more details.
Example:
fetchSync('SendMessage', '/message', { body: 'Hello, World!' })const sync = fetchSync.get('SendMessage')
sync.then((response) => { if (response.ok) { alert(
Your message was received at ${new Date(sync.syncedOn).toDateString()}.
} else { alert('Message failed to send.') } })
fetchSync.getAll() : Array
Get all sync operations.
Returns an array of all sync operations (named and unnamed).
Example:
fetchSync.getAll() .then((syncs) => syncs.forEach(sync => sync.cancel()))
fetchSync.cancel(name) : Promise
Cancel the sync with the given
name.
Example:
fetchSync('Update', '/update', { body }) fetchSync.cancel('Update')
fetchSync.cancelAll() : Promise
Cancel all syncs, named and unnamed.
sync.cancel() : Promise
Cancels the sync operation.
Returns a Promise of success of the cancellation.
Example:
const sync = fetchSync.get('Update') sync.cancel()
sync.id
The unique ID of the sync operation. This will be its name if it has one.
sync.name
The name of the sync operation if it has one.
sync.createdOn
The time that the sync operation was created.
sync.syncedOn
The time that the sync operation was completed.
As the library depends on Service Workers and no headless browser has (good enough) support for Service Workers that would allow tests to be executed within the console, tests are ran through the browser using Mocha and Chai.
On running
npm testan Express server will be started at
localhost:8000.
Run the tests:
$ cd fetch-sync $ npm test
The library is bundled by Webpack and transpiled by Babel.
npm install
npm run watch
npm test
http://localhost:8000
All pull requests and issues welcome!
If you're not sure how, check out Kent C. Dodds' great video tutorials on egghead.io!
fetch-syncwas created by Sam Gluck and is released under the MIT license.