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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: " + e.data);
  // 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

FeatureChromeEdgeFirefoxInternet ExplorerOperaSafari
Basic support60 ?54 No47 No
FeatureAndroid webviewChrome for AndroidEdge mobileFirefox for AndroidOpera AndroidiOS SafariSamsung Internet
Basic support6060 ?5447 No ?

Document Tags and Contributors

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