heir.js

/**
 * Heir v4.0.0 - http://git.io/F87mKg
 * Oliver Caldwell - https://oli.me.uk/
 * Unlicense - http://unlicense.org/
 */

const heir = {
  /**
   * Causes your desired class to inherit from a source class. This uses
   * prototypical inheritance so you can override methods without ruining
   * the parent class.
   *
   * This will alter the actual destination class though, it does not
   * create a new class.
   *
   * @param {Function} destination The target class for the inheritance.
   * @param {Function} source Class to inherit from.
   * @param {Boolean} addSuper Should we add the _super property to the destination object? Defaults to true.
   */
  inherit: function inherit (destination, source, addSuper) {
    const proto = destination.prototype = Object.create(source.prototype)
    proto.constructor = destination

    if (addSuper || typeof addSuper === 'undefined') {
      destination._super = source.prototype
    }
  },

  /**
   * Mixes the specified object into your class. This can be used to add
   * certain capabilities and helper methods to a class that is already
   * inheriting from some other class. You can mix in as many object as
   * you want, but only inherit from one.
   *
   * These values are mixed into the actual prototype object of your
   * class, they are not added to the prototype chain like inherit.
   *
   * @param {Function} destination Class to mix the object into.
   * @param {Object} source Object to mix into the class.
   */
  mixin: function mixin (destination, source) {
    let key

    for (key in source) {
      if (source.hasOwnProperty(key)) {
        destination.prototype[key] = source[key]
      }
    }
  }
}

module.exports = heir