Passive Events: tests

 from Red Blob Games
9 Feb 2023

MDN documentation[1] states that “browsers other than Internet Explorer and Safari” make some event listeners passive by default. In another project it seemed like it was Chrome and Safari that made those event listeners passive by default. I set this page up to test across browsers.

Test results: all modern browsers make these event listeners passive by default.

Here’s the side by side test, with the default setting on the left (page) and active event listener on the right (page). After attempting to scroll, scrolled tells us we could not prevent scrolling.

wheel events, desktop:

touchstart and touchmove events:

I did not have a machine where I can test touch events on desktop (Windows)

Desktop Chrome produced this error

[Intervention] Unable to preventDefault inside passive event listener due to target being treated as passive. See

Desktop Firefox produced this warning

Ignoring ‘preventDefault()’ call on event of type ‘wheel’ from a listener registered as ‘passive’.

Desktop Safari did not produce any error or warning.[2] says

If the event is not cancelable, then its cancelable property will be false and the event listener cannot stop the event from occurring.

However it looks like Firefox currently sets cancelable to true even though the event is not cancelable. (bug[3])

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