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.

We’d love to hear your thoughts on the next set of proposals for the JavaScript language. You can find a description of the proposals here.
Please take two minutes to fill out our short survey.

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