inheritence-stuff-es6.js

'use strict';

class Readable {
  constructor() {
    this._onreadable = null;

    // Acquire the default onreadable callback if it's been set.
    if (typeof this.constructor._onreadable === 'function')
      this._onreadable = this.constructor._onreadable;
  }

  static onreadable(cb) {
    if (typeof cb !== 'function')
      throw new TypeError('callback must be a function');
    this._onreadable = cb;
  }
}

Readable._onreadable = null;



// Extending this

class MyReadable extends Readable {
  constructor() {
    super();
  }
}

// Don't want the internal Object Map to change, so still have to do this.
MyReadable._onreadable = undefined;


class MyReadable2 extends Readable {
  constructor() {
    super();
  }
}

// Don't want the internal Object Map to change, so still have to do this?
MyReadable2._onreadable = undefined;

print(Object.keys(MyReadable));


Readable.onreadable(function foo() { });
MyReadable.onreadable(function bar() { });
MyReadable2.onreadable(function baz() { });



let r = new Readable();
//print(Readable._onreadable);    // output: function foo() { }
//print(r._onreadable);           // output: function foo() { }


let mr = new MyReadable();
//print(MyReadable._onreadable);  // output: function bar() { }
//print(mr._onreadable);          // output: function bar() { }


let mr2 = new MyReadable2();
//print(MyReadable2._onreadable); // output: function baz() { }
//print(mr2._onreadable);         // output: function baz() { }