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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 focused read-only property of the WindowClient interface is a Boolean that indicates whether the current client has focus.


myFocused = WindowClient.focused;


A Boolean.


self.addEventListener('notificationclick', function(event) {
  console.log('On notification click: ', event.notification.tag);

  // This looks to see if the current is already open and
  // focuses if it is
    type: "window"
  }).then(function(clientList) {
    for (var i = 0; i < clientList.length; i++) {
      var client = clientList[i];
      if (client.url == '/' && 'focus' in client) {
          return client.focus();
    if (clients.openWindow)
      return clients.openWindow('/');


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

Browser compatibility

Feature Chrome Firefox (Gecko) Internet Explorer Opera Safari (WebKit)
Basic support 42.0 44.0 (44.0)[1] No support ? 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 42.0

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

Document Tags and Contributors

 Contributors to this page: chrisdavidmills, rolfedh, Sebastianz
 Last updated by: chrisdavidmills,