js-inheritance-lib-objects-only

var Lib2 = {
  extend: function (props) {
		var sub = Object.create(this);
		sub = mixin(sub, props);
		sub.super = this;
		return sub;
	}
};

var Person = Lib.extend({
  init: function (name) {
		this.name = name;
	},
	speak: function () {
		console.log(this.name);
	}
});

var Employee = Person.extend({
	work: function () {
		console.log(this.name + ' is working');
	}
});

var d = Employee.extend();
d.init('chris');
d.speak();
d.work();