Passive Event Listener

Test plan: use mousewheel. Can be used to dramatically improve scrolling performance. The browser can then, for example, keep scrolling at native speed without waiting for your event handlers to finish executing. Demo. Passive Event Listeners allow you to attach un-cancelable handlers to events, letting browsers optimize around your event listeners. Passive listeners cannot cancel event propagation. When a wheel event propagates outside of the canvas it can drastically slow down the browser as the parent elements try to compute whether or not they can scroll. Introducing { passive: true } Now, thanks to EventListenerOptions you have the ability to tell the browser that you just want to do your stuff and you are not gonna call preventDefault. Implement the behaviour with respect to dispatching passive EventListeners so that calling preventDefault inside executing the passive registered callback only generates a warning to the console. Expose "passive" boolean in the EventListenerOptions dictionary. This change uses manual event listener management to add active listeners, which is inline w/ the behavior for chrome before version 73. Passive event listeners User input.