JavaScript Object Prototype

PrototypeIt is a mechanism by which JavaScript objects inherit features from each other.

In the previous chapter, we learned how to useConstructor:

function User(fname, lname, age, loc) {
　　　this.firstName = fname;
　　　this.lastName = lname;
　　　this.age = age;
　　　this.location = loc;
}
var Seagull = new User("Seagull", "Anna",　22, "New Delhi");
var tarush = new User("Tarush", "Balodhi",　34, "Bihar");

We also learned thatCannotAdd the new property to the existing object constructor:

User.weapon = "Sword";

function User(fname, lname, age, loc) {
　　　this.firstName = fname;
　　　this.lastName = lname;
　　　this.age = age;
　　　this.location = loc;
　　　this.weapon = "Sword";
}

Sometimes we want to add new properties and methods to a constructor later, which will be shared among all objects (examples). The answer is the objectPrototype.

Using the Prototype Property

The prototype property allows you to add properties and methods to the constructor.

In this example, the prototype property allows you to add new properties to the User object constructor:

function User(fname, lname, age, loc) {
　　　this.firstName = fname;
　　　this.lastName = lname;
　　　this.age = age;
　　　this.location = loc;
}
User.prototype.weapon = "Sword";

In this example, the prototype property allows you to add new methods to the User object constructor:

function User(fname, lname, age, loc) {
　　　this.firstName = fname;
　　　this.lastName = lname;
　　　this.age = age;
　　　this.location = loc;
}
User.prototype.fullName = function() {
return this.firstName　+　"　"　+　this.lastName;
};

Note:Only modify your own prototype. Do not modify the prototype of standard (built-in) JavaScript objects.