license /** Cached result of whether the user's browser supports passive event listeners. */ let supportsPassiveEvents ; /**
 * Checks whether the user's browser supports passive event listeners.
 * See: https://github.com/WICG/EventListenerOptions/blob/gh-pages/explainer.md
 */ export function supportsPassiveEventListeners ( ) { if ( supportsPassiveEvents == null && typeof window !== 'undefined' ) { try { window . addEventListener ( 'test' , null ! , Object . defineProperty ( { } , 'passive' , { get : ( ) => ( supportsPassiveEvents = true ) , } ) ) ; } finally { supportsPassiveEvents = supportsPassiveEvents || false ; } } return supportsPassiveEvents ; } param options export function normalizePassiveListenerOptions ( options ) { return supportsPassiveEventListeners ( ) ? options : ! ! options . capture ; }