Get javascript class name or typeof in parent constructor

Question

I have two classes in Javascript like this:

class Parent {
    constructor(){
        console.log(typeof this);
    }
}

class Child extends Parent {
    constructor(){
        super();
    }
}

In the Parent class, I would like to know what class instantiated it. However, typeof just returns object. Is there any other way to solve this?

What exactly do you need this for? This sounds like an XY problem. — Bergi
– Bergi, Commented Sep 29, 2016 at 18:47
I intend to let the Parent class handle methods like save and get, and unless anything else is specified, it will look in tables that are named lowercase of the calling class. So if I instantiate a child, and run child.save() i'll let the Parent.save method save the object to a table called "child" — Ole Haugset
– Ole Haugset, Commented Sep 29, 2016 at 19:14
I would recommend to pass the table name explicitly as a parameter to the parent constructor. Relying on the child constructor name has several problems: it might not work in pre-ES6 environments, it breaks the LSP, and there might be anonymous subclasses or duplicate names. — Bergi
– Bergi, Commented Sep 29, 2016 at 19:57

Felix Kling · Accepted Answer · 2016-09-29 18:41:03Z

3

this.constructor will return the constructor function with which the objet was created. You could access this.constructor.name if you need a string.

class Parent {
    constructor(){
        console.log(this.constructor.name);
    }
}

class Child extends Parent {
    constructor(){
        super();
    }
}

new Child(); // Child
new Parent(); // Parent

answered Sep 29, 2016 at 18:41

Felix Kling

820k181 gold badges1.1k silver badges1.2k bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Community · Accepted Answer · 2017-05-23 10:27:46Z

1

Since you are using ES6 classes, new.target is what you are looking for. But notice that it's usually an antipattern to let a constructor's behaviour depend on particular child classes.

edited May 23, 2017 at 10:27

CommunityBot

11 silver badge

answered Sep 29, 2016 at 18:45

Bergi

671k162 gold badges1k silver badges1.5k bronze badges

Collectives™ on Stack Overflow

Get javascript class name or typeof in parent constructor

2 Answers 2

Comments

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related