(function () {

  'use strict';

  //JS

  window.onload = function () {

    var elem = document.querySelector('.list__item');

    var classNames = elem.className;

​

    elem.addEventListener('click', function () {

        //elem.classList.add('list__item--active');

        elem.className = classNames + ' list__item--active';        

    }, false);

  };

​

  //jQuery

  /*

  $(function () {

    $('.list__item').on('click', function () {

       $(this).addClass('list__item--active');

    });

  });

  */

})();