Object prototype (Object constructor function) basic example.

object.js

var txt = "";
var x;

function Person(first, last, age, sex) { //Object prototype (Object constructor function)
    this.firstName = first;
    this.lastName = last;
    this.age = age;
    this.sex = sex;
    this.changeFirstName = function (name) {
        this.firstName = name;
    };
}

var you = new Person("Nydia", "Garz", 50, "F");
var me = new Person("Carlos", "Rami", 25, "M");

you.changeFirstName('Nxdxa');
you.nationality = "English"; //Adding property.
me.fullName = function(){ return this.firstName + " " + this.lastName } //Adding function.
delete you.age;   //Deleting property. Or delete you["age"];

/*
It isn't posible add a new property to a prototype the same way as add a new property to an 
existing object, because the prototype is not an existing object. Then, this is the way:
The JavaScript prototype property allows you to add new properties or methods to an existing prototype:
*/

Person.prototype.race = "Latin";
/*
Person.prototype.race;
you.race =  "Latin";
me.race = "White";
*/

console.log("Your first name is " + you.firstName + ", your race is " + you.race +  ". I'm " + me.age + " years old and my fullname is " + me.fullName() + ", my race is " + me.race + ".");

for (x in me) {  //Exploring object's properties.
    txt += me[x] + "\n";
}

console.log('Txt: \n' + txt);