quick smooth scroll

smoothScrollTo.js

// smooth scroll
var now = window.performance && window.performance.now ? window.performance.now.bind(window.performance): Date.now
var SCROLL_TIME = 468

export function smoothScrollTo({ element, y, startY, startTime }) {
	startTime = startTime || now()
	var time = now()
	var elapsed = (time - startTime) / SCROLL_TIME;

	// avoid elapsed times higher than one
	elapsed = elapsed > 1 ? 1 : elapsed

	// apply easing to elapsed time
	var value = 0.5 * (1 - Math.cos(Math.PI * elapsed))

	var currentY = startY + (y - startY) * value

	element.scrollTop = currentY
	
	// scroll more if we have not reached our destination
	if (currentY !== y) {
		window.requestAnimationFrame(smoothScrollTo.bind(window, { element, y, startY, startTime }))
	}
}

smoothScrollTo({
	element: domElement,
	y: 100,
	startY: domElement.scrollTop
})