npm install nextmatchingelement --save

var nextEl = require('nextmatchingelement');

nextEl(el, target, callback);

el is the starting element, from which the sibling will be found.

target is the target element you'd like to select

callback is the callback function you'd like to run once the target element has been found. It takes one argument which is a DOM node of the nextElementSibling found.

	<h3 class="findNext"></h3>
	<p>Lorem ipsum dolor sit amet, consectetur adipisicing elit. Sit dolore commodi, et fuga quas.</p>
	<div class="demo">
		Foo
	</div>

var findNext = document.querySelector('.findNext');
nextEl(findNext, 'demo', function (target) {
	target.classList.toggle('show-code');
});