In Javascript, not many functions support interaction between objects and classes. Here I will use some methods like the instanceof
keywords and prototype.isPrototypeOf()
to get an object’s class in JavaScript by checking if it is an object of that class. Follow the article to better understand.
Get An Object’s Class In JavaScript
Method 1: Use instanceof keywords
Instanceof
keywords are used to check if this object belongs to this class, and the return result of instanceof
keywords is a boolean value. If the returned result is true, we have the suitable object for the class we need.
Syntax:
myObj isntanceof className
Parameters:
- myObj: Is the object to be checked
- className: is the name of the class you want to check if the object myObj belongs to it
Example 1:
class Cls1 {} class Cls2 {} var myObj = new Cls1(); console.log(myObj instanceof Cls1); console.log(myObj instanceof Cls2);
Output:
true
false
In the above example, we see that myObj is not of ‘Cls2’ class , so the return value of instanceof
returns false. The result returns true when we test it with ‘Cls1’ class, from which we get myObj of ‘Cls1’ class.
Example 2:
class Animal {} class Person {} var dog = new Animal(); console.log(dog instanceof Animal); console.log(dog instanceof Person);
Output:
true
false
Similar to the example above, we see that ‘dog’ is not of the ‘Person’ class, so the return value of instanceof
is false. In case we test it with the ‘Animal’ class, the result is true, so ‘dog’ is an object of the ‘Animal’ class. As in the two examples above, we can check whether an object belongs to that class or not, from which we get an object from a class you want.
Method 2: Use prototype.isPrototypeOf() method
This method is similar to method one and returns a boolean.
Syntax:
classname.prototype.isPrototypeOf(myObj)
Parameters:
- myObj: Is the object to be checked
- className: is the name of the class you want to check if the object myObj belongs to it
Example 1:
class Cls1 {} class Cls2 {} var myObj = new Cls1(); console.log(Cls1.prototype.isPrototypeOf(myObj)); console.log(Cls2.prototype.isPrototypeOf(myObj));
Output:
true
false
When we check myObj with the prototype.isPrototypeOf()
, we see that myObj is an object of Cls1, so the return result is true and vice versa because when compared with Cls2, we get the result false.
Example 2:
class Animal {} class Person {} var cat = new Animal(); console.log(Animal.prototype.isPrototypeOf(cat)); console.log(Person.prototype.isPrototypeOf(cat));
Output:
true
false
Similarly, the cat is an animal, not a person, so the result of the first line is true, and is false otherwise. The cat is not a person, so the second line is false.
Summary
In this tutorial, I showed several ways to get an object’s class in JavaScript. I hope this article helps you and your program. If you have any questions or problems, please comment below. I will respond as possible. Thank you for your reading!
Maybe you are interested:
- Access the First Property of an Object in JavaScript
- How to get the Class Name of an Object in JavaScript
- Check if an object is empty in JavaScript

My name is Tom Joseph, and I work as a software engineer. I enjoy programming and passing on my experience. C, C++, JAVA, and Python are my strong programming languages that I can share with everyone. In addition, I have also developed projects using Javascript, html, css.
Job: Developer
Name of the university: UTC
Programming Languages: C, C++, Javascript, JAVA, python, html, css