This is an experimental technology
Check the Browser compatibility table carefully before using this in production.

The type read-only property of the Client interface indicates the type of client the service worker is controlling.


var myClientType = Client.type;


A string, representing the client type. The value can be one of

  • window
  • worker
  • sharedworker
  • all


// service worker client (e.g. a document)
function sendMessage(message) {
  return new Promise(function(resolve, reject) {
    // note that this is the ServiceWorker.postMessage version
    window.serviceWorker.onMessage = function(e) {

// controlling service worker
self.addEventListener("message", function(e) {
  // e.source is a client object
  e.source.postMessage("Hello! Your message was: " +;
  // Let's also post the type value back to the client


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

Browser compatibility

Update compatibility data on GitHub
ChromeEdgeFirefoxInternet ExplorerOperaSafariAndroid webviewChrome for AndroidEdge MobileFirefox for AndroidOpera for AndroidSafari on iOSSamsung Internet
Basic support
Chrome Full support 60Edge ? Firefox Full support 54IE No support NoOpera Full support 47Safari No support NoWebView Android Full support 60Chrome Android Full support 60Edge Mobile ? Firefox Android Full support 54Opera Android Full support 47Safari iOS No support NoSamsung Internet Android No support No


Full support  
Full support
No support  
No support
Compatibility unknown  
Compatibility unknown
Experimental. Expect behavior to change in the future.
Experimental. Expect behavior to change in the future.

Document Tags and Contributors

Contributors to this page: fscholz, jpmedley, jan.roudaut, chrisdavidmills
Last updated by: fscholz,