ServiceWorkerContainer.controller

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

Syntax

var myController = navigator.serviceWorker.controller;

Example

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.';
}

Specifications

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

Browser compatibility

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