cho bind

(function (win, doc) {
  'use strict';
			    
  var bind = win.addEventListener ? 'addEventListener' : 'attachEvent',
      unbind = win.removeEventListener ? 'removeEventListener' : 'detachEvent',
      prefix = (bind !== 'addEventListener') ? 'on' : '',
      cho = win.cho || {};
  
  /**
   * Created by https://github.com/component/event/blob/master/index.js
   * @param {Element} el
   * @param {String} type
   * @param {Function} fn
   * @param {Boolean} capture
   * @return {Function}
   * @see https://github.com/component/event/blob/master/index.js
   */
  cho.bind = function (el, type, fn, capture) {
      el[bind](prefix + type, fn, capture || false);
      return fn;
  };
  
  /**
   * Created by https://github.com/component/event/blob/master/index.js
   * @param {Element} el
   * @param {String} type
   * @param {Function} fn
   * @param {Boolean} capture
   * @return {Function}
   * @api public
   */
  
  cho.unbind = function (el, type, fn, capture) {
      el[unbind](prefix + type, fn, capture || false);
      return fn;
  };

}(this, this.document));