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This is an experimental technology
Because this technology's specification has not stabilized, check the compatibility table for usage in various browsers. Also note that the syntax and behavior of an experimental technology is subject to change in future versions of browsers as the specification changes.

The controller read-only property of the ServiceWorkerContainer interface returns a ServiceWorker object if its state is activated (the same object returned by This property returns null if the request is a force refresh (Shift + refresh) or if there is no active worker.


var myController = navigator.serviceWorker.controller;


if ('serviceWorker' in navigator) {
  navigator.serviceWorker.register('service-worker.js', {scope: './'}).then(function(r) {
    if (navigator.serviceWorker.controller) {
      document.querySelector('#status').textContent = 'A service worker is currently handling network operations.';
    } else {
      document.querySelector('#status').textContent = 'Please reload this page to allow the service worker to handle network operations.';
  }).catch(function(error) {
    document.querySelector('#status').textContent = error;
} else {
  document.querySelector('#status').textContent = 'Service workers are not supported.';


Specification Status Comment
Service Workers
The definition of 'ServiceWorkerRegistration.controller' in that specification.
Working Draft Initial definition

Browser compatibility

Feature Chrome Firefox (Gecko) Internet Explorer Opera Safari (WebKit)
Basic support 40.0 44.0 (44.0)[1] No support 24 No support
Feature Android Firefox Mobile (Gecko) Firefox OS IE Mobile Opera Mobile Safari Mobile Chrome for Android
Basic support ? 44.0 (44.0) (Yes) No support ? No support ?

[1] Service workers (and Push) have been disabled in the Firefox 45 Extended Support Release (ESR.)

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 Last updated by: ithinkihaveacat,