(function (root, factory) {
  if (typeof define === 'function' && define.amd) {
    define(factory);
  } else if (typeof exports === 'object') {
    module.exports = factory;
  } else {
    root.apollo = factory();
  }
})(this, function () {

  'use strict';

  var apollo = {};

  var hasClass, addClass, removeClass, toggleClass;

  var forEach = function (items, fn) {
    if (Object.prototype.toString.call(items) !== '[object Array]') {
      items = items.split(' ');
    }
    for (var i = 0; i < items.length; i++) {
      fn(items[i], i);
    }
  };

  if ('classList' in document.documentElement) {
    hasClass = function (elem, className) {
      return elem.classList.contains(className);
    };
    addClass = function (elem, className) {
      elem.classList.add(className);
    };
    removeClass = function (elem, className) {
      elem.classList.remove(className);
    };
    toggleClass = function (elem, className) {
      elem.classList.toggle(className);
    };
  } else {
    hasClass = function (elem, className) {
      return new RegExp('(^|\\s)' + className + '(\\s|$)').test(elem.className);
    };
    addClass = function (elem, className) {
      if (!hasClass(elem, className)) {
        elem.className += (elem.className ? ' ' : '') + className;
      }
    };
    removeClass = function (elem, className) {
      if (hasClass(elem, className)) {
        elem.className = elem.className.replace(new RegExp('(^|\\s)*' + className + '(\\s|$)*', 'g'), '');
      }
    };
    toggleClass = function (elem, className) {
      (hasClass(elem, className) ? removeClass : addClass)(elem, className);
    };
  }

  apollo.hasClass = function (elem, className) {
    return hasClass(elem, className);
  };

  apollo.addClass = function (elem, classes) {
    forEach(classes, function (className) {
      addClass(elem, className);
    });
  };

  apollo.removeClass = function (elem, classes) {
    forEach(classes, function (className) {
      removeClass(elem, className);
    });
  };

  apollo.toggleClass = function (elem, classes) {
    forEach(classes, function (className) {
      toggleClass(elem, className);
    });
  };

  return apollo;

});