How to Get a Javascript Object’s Class?

How to Get a JavaScript Object’s Class

When working with JavaScript, you may come across situations where you need to determine the class of an object. While JavaScript does not have built-in support for classes like other programming languages, you can still determine the class of an object using various techniques. In this article, we will explore a few methods to accomplish this task.

Method 1: Using the instanceof Operator

The instanceof operator allows you to check if an object is an instance of a particular class or constructor function. It returns true if the object is an instance of the specified class, and false otherwise.

class Person {
  constructor(name) {
    this.name = name;
  }
}

const person = new Person('John');

console.log(person instanceof Person); // true

In the above example, we create a class called Person and instantiate an object person from it. By using the instanceof operator, we can check if person is an instance of the Person class, which returns true.

Method 2: Using the constructor Property

Every JavaScript object has a constructor property that refers to the constructor function used to create the object. By accessing this property, we can determine the class of an object.

class Car {
  constructor(make, model) {
    this.make = make;
    this.model = model;
  }
}

const car = new Car('Toyota', 'Camry');

console.log(car.constructor.name); // Car

In the above example, we define a class Car and create an object car from it. By accessing the constructor.name property of car, we can retrieve the name of the constructor function, which in this case is Car.

Method 3: Using the Object.prototype.toString() Method

The Object.prototype.toString() method returns a string representation of the object. By calling this method on an object, we can extract the class information from the resulting string.

class Animal {
  constructor(name) {
    this.name = name;
  }
}

const animal = new Animal('Lion');

console.log(Object.prototype.toString.call(animal)); // [object Object]

In the above example, we define a class Animal and create an object animal from it. By calling Object.prototype.toString.call(animal), we get the string representation of animal, which is [object Object]. Although this method does not directly provide the class name, it can still be useful in certain scenarios.

These are a few methods you can use to get the class of a JavaScript object. Depending on your specific requirements, you can choose the most suitable method for your use case.

Remember, JavaScript does not have built-in classes like other languages, but these techniques can help you determine the class of an object in JavaScript.

Happy coding!