ui.js

(function (window, document) {

 var layout = document.getElementById('layout'),
 menu = document.getElementById('menu'),
 menuLink = document.getElementById('menuLink');

 function toggleClass(element, className) {
 var classes = element.className.split(/\s+/),
 length = classes.length,
 i = 0;

 for(; i < length; i++) {
 if (classes[i] === className) {
 classes.splice(i, 1);
 break;
 }
 }
 // The className is not found
 if (length === classes.length) {
 classes.push(className);
 }

 element.className = classes.join(' ');
 }

 menuLink.onclick = function (e) {
 var active = 'active';

 e.preventDefault();
 toggleClass(layout, active);
 toggleClass(menu, active);
 toggleClass(menuLink, active);
 };

}(this, this.document));