Ocena kodu javascript cz2.

Witam ponownie, poprawiłem lekko kod i czekam na opinię. Teraz kod jest w miarę akceptowalny, czy nadal nie jest zgodny ze standardami itp? 

(function() {

	var number = 0;
	var timer;
	var timer2;
	var timer3;
	var slide = document.querySelector(".slide");
	var preview = document.querySelector(".left");
	var next = document.querySelector(".right");	
	
	function changeslide()
	{
		timer2 = setTimeout(flash, 5000);
		timer3 = setTimeout(flash2, 5500);
		number++;
		if (number > 4) number=1;
		if (number < 1) number=4;
		slide.src = "images/" + number + ".png";
		timer = setTimeout(changeslide, 5000);
	}
	
	function minus()
	{
		clearTimeout(timer);
		clearTimeout(timer2);
		clearTimeout(timer3);
		timer2 = setTimeout(flash, 100);
		timer3 = setTimeout(flash2, 500);
		number=number-2;
		changeslide();
	}
	
	function plus()
	{
		clearTimeout(timer);
		clearTimeout(timer2);
		clearTimeout(timer3);
		timer2 = setTimeout(flash, 100);
		timer3 = setTimeout(flash2, 500);		
		clearTimeout(timer);
		changeslide();
	}
	
	function flash()
	{
		slide.className = "slide" + "" + "wow fadeIn animated";
	}
	function flash2()
	{
		slide.className = "slide";
	}
	
	preview.addEventListener("click", minus);
	next.addEventListener("click", plus);
		
	changeslide();
	
})();