Factory Design Pattern in Typescript

Javascript is not enough to implement ordinary factory design patternt that I want to mimic from C#, therefore I try to do it on Typescript, though nested class declaration is still not that straight forward in typescript:

class Point {
  x: number;
  y: number;

  private constructor(x: number, y: number) {
    this.x = x;
    this.y = y;
  }

  static Factory = class {
    static pointXY(x: number, y: number) {
      return new Point(x, y);
    }
    static pointPolar(r: number, theta: number) {
      return new Point(
        r * Math.cos((theta * Math.PI) / 180),
        r * Math.sin((theta * Math.PI) / 180)
      );
    }
  };
}

now we can create our point by calling

const pt = Point.Factory.pointXY(10, 20);