Web features explorer

Observable

Limited availability

This feature has received a negative standards position from at least one browser vendor — It's very unlikely to ever become Baseline in this current form.

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.

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 Not supported Position: negative (concerns: complexity, venue, API design) Bugs: 1871732
  • Firefox for Android Not supported Position: negative (concerns: complexity, venue, API design)
  • Safari Not supported Position: support (concerns: venue)
  • Safari on iOS Not supported Position: support (concerns: venue)

MDN documentation

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.

Specifications

Usage (according to Chrome Platform Status)

~0.000% of page loads. More data at chromestatus.com.

Web Platform Tests (WPT)

View the latest WPT test results for this feature

View as JSON | Edit this feature | Report an issue | Web-features entry: source, dist