OLOO (objects linked to other objects) pattern explored (with comparison to the prototype style of the same code)

ex1-prototype-style.js

function Foo(who) {
	this.me = who;
}

Foo.prototype.identify = function() {
	return "I am " + this.me;
};

function Bar(who) {
	Foo.call(this,"Bar:" + who);
}

Bar.prototype = Object.create(Foo.prototype);
Bar.prototype.constructor = Bar;    // "fixes" the delegated `constructor` reference

Bar.prototype.speak = function() {
	alert("Hello, " + this.identify() + ".");
};

var b1 = new Bar("b1");
var b2 = new Bar("b2");

b1.speak(); // alerts: "Hello, I am Bar:b1."
b2.speak(); // alerts: "Hello, I am Bar:b2."

// some type introspection
b1 instanceof Bar; // true
b2 instanceof Bar; // true
b1 instanceof Foo; // true
b2 instanceof Foo; // true
Bar.prototype instanceof Foo; // true
Bar.prototype.isPrototypeOf(b1); // true
Bar.prototype.isPrototypeOf(b2); // true
Foo.prototype.isPrototypeOf(b1); // true
Foo.prototype.isPrototypeOf(b2); // true
Foo.prototype.isPrototypeOf(Bar.prototype); // true
Object.getPrototypeOf(b1) === Bar.prototype; // true
Object.getPrototypeOf(b2) === Bar.prototype; // true
Object.getPrototypeOf(Bar.prototype) === Foo.prototype; // true

ex2-oloo-style.js

var Foo = {
	Foo: function(who) {
		this.me = who;
		return this;
	},
	identify: function() {
		return "I am " + this.me;
	}
};

var Bar = Object.create(Foo);

Bar.Bar = function(who) {
	// "constructors" (aka "initializers") are now in the `[[Prototype]]` chain,
	// so `this.Foo(..)` works easily w/o any problems of relative-polymorphism
	// or .call(this,..) awkwardness of the implicit "mixin" pattern
	this.Foo("Bar:" + who);
	return this;
};

Bar.speak = function() {
	alert("Hello, " + this.identify() + ".");
};

var b1 = Object.create(Bar).Bar("b1");
var b2 = Object.create(Bar).Bar("b2");

b1.speak(); // alerts: "Hello, I am Bar:b1."
b2.speak(); // alerts: "Hello, I am Bar:b2."

// some type introspection
Bar.isPrototypeOf(b1); // true
Bar.isPrototypeOf(b2); // true
Foo.isPrototypeOf(b1); // true
Foo.isPrototypeOf(b2); // true
Foo.isPrototypeOf(Bar); // true
Object.getPrototypeOf(b1) === Bar; // true
Object.getPrototypeOf(b2) === Bar; // true
Object.getPrototypeOf(Bar) === Foo; // true

I believe through this practice the key takeaway is Behavior Delegation of objects linking to other objects.

OLOO for the win. Also add this to Foo:

  [Symbol.hasInstance](instance) {
    return this.isPrototypeOf(instance)
  }

so this will work fine too:

b1 instanceof Bar; // true
b2 instanceof Bar; // true
b1 instanceof Foo; // true
b2 instanceof Foo; // true