Highlight an element and fade highlight after a delay

HighlightElement.js

function HighlightItem(delay, element) {
	var startTime = -1;
	var duration = 3000;
	var startC = [255, 255, 255, 0];
	var highlightC = [255, 255, 100, 1];

	element.style.backgroundColor = "rgba(" + highlightC.join() + ")";

	function highlightLoop(){
		var t = (Date.now() - startTime) / duration;
		if (t > 1) {
			return;
		}

		t = Math.sin(t * (Math.PI) + Math.PI/2) / 2 + 0.5;
		var color = [LerpColor(startC[0], highlightC[0], t), LerpColor(startC[1], highlightC[1], t), LerpColor(startC[2], highlightC[2], t), Lerp(startC[3], highlightC[3], t)]
		element.style.backgroundColor = "rgba(" + color.join() + ")";

		window.requestAnimationFrame(highlightLoop);
	};

	setTimeout(function() {
		startTime = Date.now();
		highlightLoop();
	}, delay);
}

function LerpColor(from, to, t) {
	return Math.floor(Lerp(from, to, t));
};

function Lerp(from, to, t) {
	return (to - from) * t + from;
}