inheritance.js

"use strict";

// Base Girl object.
function Girl() {
    this.name = '';
    this.traits = {};
}

// Scout `is a` Girl
function Scout() {
    Girl.call(this);
    this.team = '';
}

Scout.prototype = new Girl();
Scout.prototype.constructor = Scout;

// Setup scout: Sarah
var sarah = new Scout();
sarah.name = "Sarah";
sarah.team = "Blue Scouts";
sarah.traits.age = 30;
sarah.traits.weight = 125;

// Setup scout: Tricia
var tricia = new Scout();
tricia.name = "Tricia";
tricia.team = "Green Scouts";
tricia.traits.age = 32;
tricia.traits.weight = 140;

// Log the girls
console.log("Sarah:", sarah, "\n");
console.log("Tricia:", tricia, "\n");

// Sarah (and Tricia) are both girl scouts
console.log(sarah instanceof Scout);
console.log(sarah instanceof Girl);

A simple and clean example of this pattern can be seen here: http://bit.ly/1PESNli