[TS] class props and fields

classesInTS.md

class Point {
    // fields _x, _y
  constructor(private _x: number, private _y: number) {}

  // property x
  get x() {
    console.log(this._x);
    return this._x;
  }

  set x(value: number) {
    this._x = value;
  }

  // method
  drawPoint() {
      ....
  }
}