class Human {
    constructor(name, sex) {
        this.name = name;
        this.sex = sex;
    }

    describe() {
        switch (this.sex) {
        case "M": var human = "man";
        case "F": var human = "woman";
        default:  var human = "human";
        }


        alert(this.name + " is a " + human + ".");
    }
}

class Man extends Human {
    constructor(name) {
        Human.call(this, name, "M");
    }
}

class Woman extends Human {
    constructor(name) {
        Human.call(this, name, "F");
    }
}

var john = new Man("John");
john.describe();

var jane = new Woman("Jane");
jane.describe();

function Human(name, sex) {
    this.name = name;
    this.sex  = sex;
}

Human.prototype.describe = function () {
    switch (this.sex) {
    case "M": var human = "man";
    case "F": var human = "woman";
    default:  var human = "human";
    }

    alert(this.name + " is a " + human + ".");
};

Man.prototype = Object.create(Human.prototype);
Man.prototype.constructor = Man;

function Man(name) {
    Human.call(this, name, "M");
}

Woman.prototype = Object.create(Woman.prototype);
Woman.prototype.constructor = Woman;

function Woman(name) {
    Human.call(this, name, "F");
}

var john = new Man("John");
john.describe();

var jane = new Woman("Jane");
jane.describe();

var human = {
    constructor: function (name, sex) {
        this.name = name;
        this.sex  = sex;
    },
    describe: function () {
        switch (this.sex) {
        case "M": var human = "man";
        case "F": var human = "woman";
        default:  var human = "human";
        }


        alert(this.name + " is a " + human + ".");
    }
};

var man = Object.create(human);

man.constructor = function (name) {
    human.constructor.call(this, name, "M");
};

var woman = Object.create(human);

woman.constructor = function (name) {
    human.constructor.call(this, name, "F");
};

var john = Object.create(man);
john.constructor("John");
john.describe();

var jane = Object.create(woman);
jane.constructor("Jane");
jane.describe();