JavaScript, how to get the class name of an object

Apr 29, 2022

Learn how to get the class name of an object in JavaScript by reading its constructor name property, plus how to compare the constructor to a class directly.

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Suppose you have an object that’s generated from a class, and you want to get its class name.

For example, let’s use this code as reference:

class Dog {
  
}

const roger = new Dog()

Of course now we know that roger is an object that’s created from the class Dog.

But how do you get the class name of the object, in case you don’t know it?

You can lookup the object’s constructor, then reference its name property.

In this example:

class Dog {
  
}

const roger = new Dog()

console.log(roger.constructor.name) // 'Dog'

Code editor showing console.log(roger.constructor.name) outputting the string 'Dog'

This method returns a string that represents the class name.

You can also directly compare the constructor property to the class, like this:

class Dog {
  
}

const roger = new Dog()

roger.constructor === Dog //true

Code editor showing roger.constructor === Dog comparison returning true

Tagged: JavaScript · All topics

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