Concept of OOP in Javascript

oop.js

function Subject(name, topics){
    this.name = name;
    this.topics = topics;
}

var subjectMath = new Subject("Maths", ["sets", "Trigonometry", "algebra"]);
var subjectScience = new Subject("Science", ["Biology", "Astronomy", "Physics"]);

function Person(name, gender, age, currentSubject, currentTopicIndex){
    this.name = name;
    this.gender = gender;
    this.age = age;
    this.currentSubject = currentSubject;
    this.currentTopicIndex = currentTopicIndex;
    this.currentTopicName = this.currentSubject.topics[currentTopicIndex];
    //this.currentTopicName = this.currentSubject.topics[currentTopicIndex + 1];
}

Person.prototype.describe = function () {
    console.log(this.name +" is " + this.gender + 
            ", age " + this.age + " and reading " +
            this.currentSubject.name + ' with topic ' + 
            this.currentTopicName);
};
Person.prototype.hello = function(){
    console.log(this.name + " says Hi");
};
Person.prototype.goToNextTopic = function () {
    this.currentTopicIndex = this.currentTopicIndex +1;
    this.currentTopicName = this.currentSubject.topics[this.currentTopicIndex];
};

var person1 = new Person("John", "Male", 21, subjectMath, 0);
var person2 = new Person("Rita", "Female", 25,subjectMath, 0);
person1.describe();
person1.hello();
person1.goToNextTopic();
person1.describe();
person1.goToNextTopic();
person1.describe();