Create object using window[class name]

Question

I have a class like this

"use strict";

class Person {
    constructor(x, y) {
        this.x = x;
        this.y = y;
    }
}

And I'd like to create a Person using window like this:

var bob = new window["Person"](0, 15);

Like done here: Instantiate a JavaScript Object Using a String to Define the Class Name

or here: Create object from string

But it's not working. I get the error:Uncaught TypeError: window.Person is not a function

Is this not possible or am I making a stupid mistake?