Client: type property

Baseline Widely available

This feature is well established and works across many devices and browser versions. It’s been available across browsers since April 2018.

Note: This feature is only available in Service Workers.

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

Value

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

  • "window"
  • "worker"
  • "sharedworker"

Examples

js
// service worker client (e.g. a document)
function sendMessage(message) {
  return new Promise((resolve, reject) => {
    // note that this is the ServiceWorker.postMessage version
    navigator.serviceWorker.controller.postMessage(message);
    window.serviceWorker.onMessage = (e) => {
      resolve(e.data);
    };
  });
}
// controlling service worker
self.addEventListener("message", (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
  e.source.postMessage(e.source.type);
});

Specifications

Specification
Service Workers
# client-type

Browser compatibility