Object constructor in javascript

Object constructor is a blueprint of an object, it is a function that is used to create an object.

function Person(first,last,age){
    this.firstname= first;
    this.lastname = last,
    this.age = age;
}

const father = new Person('Jhon','Doe',24);
const mother = new Person('Jean','Doe',28);

In those example, we call Person function two times, thereby it create two different instance of the functions, since we use new keyword, it create two different object that set into father and mother variable.

However we cannot add new properties or methods to an object constructor directly in the way we add properties or methods to an object.

    Person.nationality = "USA";
    const father = new Person('Jhon','Doe',24);
    father.nationality
    // undefined

To add new properties or new methods to the object constructor, we can use prototype

    Person.prototype.nationality = "USA";
    father.nationality
    // USA

Now every object created using the object constructor Person will have property nationality set to USA