index.js

/* Simple JavaScript Inheritance for ES 5.1
 * based on http://ejohn.org/blog/simple-javascript-inheritance/
 *  (inspired by base2 and Prototype)
 * MIT Licensed.
 */
(function (global) {
  'use strict';
  var fnTest = /xyz/.test(function () {
    xyz;
  })
    ? /\b_super\b/
    : /.*/;

  // The base Class implementation (does nothing)
  function BaseClass() {}

  // Create a new Class that inherits from this class
  BaseClass.extend = function (props) {
    var _super = this.prototype;

    // Set up the prototype to inherit from the base class
    // (but without running the init constructor)
    var proto = Object.create(_super);

    // Copy the properties over onto the new prototype
    for (var name in props) {
      // Check if we're overwriting an existing function
      proto[name] =
        typeof props[name] === 'function' && typeof _super[name] == 'function' && fnTest.test(props[name])
          ? (function (name, fn) {
              return function () {
                var tmp = this._super;

                // Add a new ._super() method that is the same method
                // but on the super-class
                this._super = _super[name];

                // The method only need to be bound temporarily, so we
                // remove it when we're done executing
                var ret = fn.apply(this, arguments);
                this._super = tmp;

                return ret;
              };
            })(name, props[name])
          : props[name];
    }

    // The new constructor
    var newClass =
      typeof proto.init === 'function'
        ? proto.hasOwnProperty('init')
          ? proto.init // All construction is actually done in the init method
          : function SubClass() {
              _super.init.apply(this, arguments);
            }
        : function EmptyClass() {};

    // Populate our constructed prototype object
    newClass.prototype = proto;

    // Enforce the constructor to be what we expect
    proto.constructor = newClass;

    // And make this class extendable
    newClass.extend = BaseClass.extend;

    return newClass;
  };

  // export
  global.Class = BaseClass;
})(this);