The when() method on a event target returns an Observable object, which provides a declarative API for subscribing to and operating on events. It's an alternative to addEventListener() callbacks.

Learning resources on MDN

No MDN documentation found. You can search for the feature on MDN. If you believe that MDN has no documentation about this feature, you can open an issue on MDN's GitHub repository.

Browser support

• Chrome 135 Released on 2025-04-01
• Chrome Android 135 Released on 2025-04-01
• Edge 135 Released on 2025-04-04
• Firefox ❌
• Firefox for Android ❌
• Safari ❌
• Safari on iOS ❌

View web-platform-tests results for this feature - View the feature source file (dist) - Edit the feature - Report an issue about this feature