call a protected method on an instance of a class in javascript

In JavaScript, we can't create access modifiers like public, private, and protected like other object-oriented programming languages. However, we can somewhat emulate protected behavior in JavaScript by using closures.

Here's an example of how to call a protected method on an instance of a class in JavaScript:

index.tsx
class MyClass {
  #protectedMethod() {
    console.log('This method is protected and cannot be called outside the class');
  }
  
  callProtectedMethod() {
    this.#protectedMethod(); // We can call the protected method within the class
  }
}

const myObj = new MyClass();

myObj.callProtectedMethod(); // This will call the protected method within the class
myObj.#protectedMethod(); // This will throw an error because we cannot call the protected method outside the class
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In the above code, we're using the private class field syntax to declare a private / protected method, denoted by the # symbol before the method name. We can call this method within the class by using this.#protectedMethod(). However, if we try to call this method outside the class, like myObj.#protectedMethod(), we'll get a syntax error.

Note that this is not true encapsulation or access modifiers, but more of a convention. It's up to the programmer to follow this convention and not call protected / private methods outside of the class.