[j0hnik]

<div class="green">1</div>
<div class="green">2</div>
<div class="green">3</div>
	<script>
[].forEach.call(document.getElementsByClassName('green'), function(el){
	el.onclick = function(){
		el.style.backgroundColor = el.style.backgroundColor =='green'?'':'green';
	};
});
	</script>