Clients

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 Clients interface provides access to Client objects. Access it via self.clients within a service worker.

Instance methods

Clients.get(): Returns a Promise for a Client matching a given id.
Clients.matchAll(): Returns a Promise for an array of Client objects. An options argument allows you to control the types of clients returned.
Clients.openWindow(): Opens a new browser window for a given URL and returns a Promise for the new WindowClient.
Clients.claim(): Allows an active service worker to set itself as the controller for all clients within its scope.

Examples

The following example shows an existing chat window or creates a new one when the user clicks a notification.

addEventListener("notificationclick", (event) => {
  event.waitUntil(
    (async () => {
      const allClients = await clients.matchAll({
        includeUncontrolled: true,
      });

      let chatClient;

      // Let's see if we already have a chat window open:
      for (const client of allClients) {
        const url = new URL(client.url);

        if (url.pathname === "/chat/") {
          // Excellent, let's use it!
          client.focus();
          chatClient = client;
          break;
        }
      }

      // If we didn't find an existing chat window,
      // open a new one:
      chatClient ??= await clients.openWindow("/chat/");

      // Message the client:
      chatClient.postMessage("New chat messages!");
    })(),
  );
});