Proxy fetch requests through the Background Sync API
npm install fetch-syncfetchSync.{get,getAll,cancel,cancelAll}().
importScripts, or handles SW registration for you.
fetch requests.
sh
npm install fetch-sync --save
`
Table of Contents
- Requirements
- Support
- __Import__
- __Initialisation__
- __Usage__
- __Sync API__
- Dependencies
- Test
- Development
- Contributing
- Author & License
Requirements
The library utilises some new technologies so currently only works in some browsers. It definitely works in
Chrome Canary
with the experimental-web-platform-features flag enabled.
The browser must support:
- Background Sync
- Service Worker
- Fetch
- IndexedDB
- [Promise] (https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Global_Objects/Promise)
Support
Chrome Canary | Chrome | Firefox | IE | Opera | Safari
:------------:|:------:|:-------:|:--:|:-----:|:-----:
✔ |✔ |✘ |✘ |✘ |✘
Initialise
__Existing Service Worker__
If your application already uses a Service Worker, you can import the fetch-sync worker using importScripts:
`js
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.
Import
__Client__
`js
// ES6
import fetchSync from 'fetch-sync'
`
`js
// CommonJS
var fetchSync = require('fetch-sync')
`
`html
`
__Worker__
See Initialise for details on importing and registering the service worker.
Usage
$3
Initialise fetchSync.
- __options__ {Object} _(optional)_ options object
Look at the documentation for sw-register
available options and for more details on Service Worker registration.
Example:
`js
// Import client lib...
// ES6
import fetchSync from 'fetch-sync'
// ES5
var fetchSync = require('fetch-sync')
`
`html
`
`js
// Initialise, passing in worker lib location...
fetchSync.init({
url: 'node_modules/fetch-sync/dist/fetch-sync.sw.js',
scope: '' // e.g. 'http://localhost:8000'
})
`
$3
Perform a sync Background Sync operation.
- [__name__] {String} _(optional)_ name of the sync operation
- __request__ {String|Request} URL or an instance of fetch Request
- [__options__] {Object} _(optional)_ fetch options object
Returns a Promise that resolves on success of the fetch request. Rejects if a sync exists with this name already.
If called with a name:
- the response will be stored and can be retrieved later using e.g. fetchSync.get('name').then(sync => sync.response).
- the response will not automatically be removed from the IDBStore in the worker. You should request
that a named sync be removed manually by using sync.remove().
- see the Sync API for more details.
Examples:
- named GET
`js
fetchSync('GetMessages', '/messages')
.then((response) => response.json())
.then((json) => console.log(json.foo))
`
- unnamed POST
`js
const post = fetchSync('/update-profile', {
method: 'POST',
body: { name: '' }
})
// cancel the sync...
post.cancel()
`
- unnamed with options
`js
const headers = new Headers();
headers.append('Authorization', 'Basic abcdefghijklmnopqrstuvwxyz');
// fetchSync accepts the same args as fetch...
fetchSync('/send-message', { headers })
`
- named with options
`js
fetchSync('/get-messages', { headers })
`
- unnamed with Request
`js
fetchSync(
new Request('/messages')
)
`
$3
Get a sync by its name.
- __name__ {String} name of the sync operation to get
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 Sync. See the Sync API for more details.
Example:
`js
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.')
}
})
`
$3
Get all sync operations.
Returns an array of all sync operations (named and unnamed).
Example:
`js
fetchSync.getAll()
.then((syncs) => syncs.forEach(sync => sync.cancel()))
`
$3
Cancel the sync with the given name.
- __name__ {String} name of the sync operation to cancel
Example:
`js
fetchSync('Update', '/update', { body })
fetchSync.cancel('Update')
`
$3
Cancel all syncs, named and unnamed.
Sync API
$3
Cancels the sync operation.
Returns a Promise of success of the cancellation.
Example:
`js
const sync = fetchSync.get('Update')
sync.cancel()
`
$3
The unique ID of the sync operation. This will be its name if it has one.
$3
The name of the sync operation if it has one.
$3
The time that the sync operation was created.
$3
The time that the sync operation was completed.
$3
Is the sync operation cancelled?
Dependencies
- idb-wrapper
- msgr
- sw-register
- serialise-request
- serialise-response
- mini-defer
Test
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 test an Express server will be started at localhost:8000.
Run the tests:
`sh
$ cd fetch-sync
$ npm test
`
Development
The library is bundled by Webpack
and transpiled by Babel.
- Install dependencies: npm install
- Start Webpack in a console: npm run watch
- Start the test server in another: npm test
- Navigate to http://localhost:8000
Contributing
All pull requests and issues welcome!
If you're not sure how, check out Kent C. Dodds'
great video tutorials on egghead.io!
Author & License
fetch-sync` was created by Sam Gluck and is released under the MIT license.