What is the primary consequence of setting ‘passive: true’ on a touch event listener?

Question

Web Development — Hard

What is the primary consequence of setting ‘passive: true’ on a touch event listener?

Accepted Answer

By default, touch event listeners can call 'preventDefault()', which forces the browser to wait for the JavaScript execution to finish before deciding whether to scroll the page. Setting 'passive: true' informs the browser that the listener will never call 'preventDefault()', allowing the browser to perform scrolling immediately, which significantly improves scroll performance and reduces jank.