Passive Event Listeners (EventListenerOptions)

An extension to the DOM event pattern to allow listeners to disable support for preventDefault, primarily to enable scroll performance optimizations. See the explainer document for an overview.

DOM Spec changes

• See the main commit in the DOM specification or pull request for full details.
• The key parts of the spec affected by this are EventTarget, Observing event listeners, and preventDefault

Status of implementations:

• Chromium: In Chrome 50 behind chrome://flags/#enable-experimental-web-platform-features, expected to ship in Chrome 51 (launch bug)
• Polyfill
• WebKit bug

Additional background on the problem:

• Ilya Grigorik's talk at Chrome Dev Summit [slides]
• Older G+ post by Rick Byers
• Demo page

Issues with and adoption by key libraries:

• Parse.ly
• jQuery
• Ember.js

History:

• Outstanding issues
• WICG discussion
• Discussion on WhatWG
• One discussion on public-pointer-events
• Earlier scroll-blocks-on proposal and discussion