The difference between calls

Tutorial
The JavaScript language
Prototypes, inheritance
Prototype methods, objects without __proto__

The difference between calls

importance: 5

Let’s create a new rabbit object:

function Rabbit(name) {
 this.name = name;
}
Rabbit.prototype.sayHi = function() {
 alert(this.name);
};
let rabbit = new Rabbit("Rabbit");

These calls do the same thing or not?

rabbit.sayHi();
Rabbit.prototype.sayHi();
Object.getPrototypeOf(rabbit).sayHi();
rabbit.__proto__.sayHi();

The first call has this == rabbit, the other ones have this equal to Rabbit.prototype, because it’s actually the object before the dot.

So only the first call shows Rabbit, other ones show undefined:

function Rabbit(name) {
 this.name = name;
}
Rabbit.prototype.sayHi = function() {
 alert( this.name );
}
let rabbit = new Rabbit("Rabbit");
rabbit.sayHi(); // Rabbit
Rabbit.prototype.sayHi(); // undefined
Object.getPrototypeOf(rabbit).sayHi(); // undefined
rabbit.__proto__.sayHi(); // undefined