Detecting when a visitor has stopped scrolling

This snippet listens for scrolling events using addEventListener, sets a delayed timeout function to run a few milliseconds after the event, but with each scroll event it clears that timeout function so it doesn’t run.

When scrolling has stopped, the delayed function doesn’t get cleared and runs.

// Setup isScrolling variable
var isScrolling;

// Listen for scroll events
window.addEventListener('scroll', function ( event ) {

	// Clear our timeout throughout the scroll
	window.clearTimeout( isScrolling );

	// Set a timeout to run after scrolling ends
	isScrolling = setTimeout(function() {

		// Run the callback
		console.log( 'Scrolling has stopped.' );

	}, 66);

}, false);

Source

https://gomakethings.com/detecting-when-a-visitor-has-stopped-scrolling-with-vanilla-javascript/