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Service Worker registration utility

Made with ❤ at @outlandish

npm version js-standard-style

Register or retrieve a Service Worker that controls the page with ease...

  • Register a Service Worker with one call to register(<options>)
  • Get an existing Service Worker with one call to register()
  • Always favours returning the active Service Worker over registering a new one, which means you can put a call to register(<options>) with options in your init procedure and it will not try to re-register the worker. Saving you having to inspect navigator.serviceWorker.ready manually, etc.


// ES6 
import register from 'sw-register'
// CommonJS 
var register = require('sw-register')
// RequireJS 
define(['sw-register'], function (register) {/*...*/})
<!-- Script, available as `window.swRegister` -->
<script src="/node_modules/sw-register/index.js"></script>


const register = require('sw-register')
// Get existing worker 
register().then((worker) => {
  const channel = new MessageChannel()
  worker.postMessage("Hey!", [channel.port2])
// Register a worker from the client 
// Worker scope depends on worker location/headers 
// Read the Service Worker docs for more details 
const registration = {
  url: '/sw.js',
  scope: '/'
// Subsequent calls with a registration object 
// will not attempt re-registration but return 
// the existing registered worker instead 
register(registration).then((worker) => {
  const channel = new MessageChannel()
  worker.postMessage("Hey!", [channel.ports2])
// Catch registration error 
register().catch((err) => {


register([options]) : Promise

Register or retrieve a Service Worker.

  • [register] {Object} Options object

Returns the Service Worker controller.

Available options (any not listed can also be passed in):

  • url (required) the URL of the service worker
  • scope (optional) the scope of the service worker
  • forceUpdate (optional) call update() on the registration?


register().then((worker) => {
  // do something with the worker
}).catch((err) => {
  // you get here if:
  // - service workers unsupported
  // - no existing worker and no options given to register one


All pull requests and issues welcome!

If you're not sure how, check out Kent C. Dodds' great video tutorials on!

Author & License

sw-register was created by Sam Gluck and is released under the MIT license.