"

From 2014.igem.org

(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));