JS: Simple solution to open navigation panel

nav.js

/**
 * Nav Toggle
 * Inspired by John's Hamburgler http://johnm.io/project/hamburgler/
 */

(function() {

	document.getElementById('js-nav').addEventListener('click', checkNav);

	window.addEventListener("keyup", function(e) {
		if (e.keyCode == 27) closeNav();
	}, false);

	function checkNav(event) {
		event.preventDefault();
		document.body.classList.contains('nav--open') ? closeNav() : openNav()
	}

	function closeNav() {
		document.body.classList.remove('nav--open');
	}

	function openNav() {
		document.body.classList.add('nav--open');
	}

})();