Unable to access internal object after instantiation

February 6, 2023

I have a very simple code with instantiated objects and I’m exposing some methods via a prototype. Here’s the code:

const MyClass = (function() {
  function MyClass() {
    this._obj = {
      1: 'dfvdfvd'
    };
  }

  function get() {
    return this._obj[1];
  }

  MyClass.prototype.take = () => {
    get.call(this);
  }

  return MyClass;
}());

let x = new MyClass();
console.log(x.take())

but I keep getting _obj as undefined. what am I missing here?

>Solution :

The issue is that MyClass.prototype.take is an arrow function, but this is undefined for all arrow functions (see MDN). Just make it a regular function.

Also, make sure to return a value from MyClass.prototype.take(), or else you’ll get undefined.

const MyClass = (function() {
  function MyClass() {
    this._obj = {
      1: 'dfvdfvd'
    };
  }

  function get() {
    return this._obj[1];
  }

  MyClass.prototype.take = function() {
    return get.call(this);
  }

  return MyClass;
}());

let x = new MyClass();
console.log(x.take())