Typescript- Abstract Class

Type Script Abstract Class:
* Cant create an instance for abstract class.
* Abstract class can also have abstract methods.
* Abstract method must be implemented in the concrete class.
Eg:
export abstract class Shape {
    constructor(private _x: number, private _y: number) {
    }
    public get x(): number {
        return this._x;
    }
    public set x(value: number) {
        this._x = value;
    }
    public get y(): number {
        return this._y;
    }
    public set y(value: number) {
        this._y = value;
    }
    getInfo(): string {
        return `x=${this._x}, y=${this._y}`;
    }
    abstract calculateArea(): number;
}

import { Shape } from './Shape';
export class Circle extends Shape {
    calculateArea(): number {
        return Math.PI * Math.pow(this._radius, 2);
    }
    constructor(theX: number, theY: number,
                private _radius: number) {
        super(theX, theY);
    }
    public get radius(): number {
        return this._radius;
    }
    public set radius(value: number) {
        this._radius = value;
    }
    getInfo(): string {
        return super.getInfo() + `, radius=${this._radius}`;
    }
}
import { Shape } from './Shape';
export class Rectangle extends Shape {
    calculateArea(): number {
        return this._width * this._length;
    }
    constructor(theX: number, theY: number,
                private _width: number, private _length: number) {
        super(theX, theY);
    }
    public get width(): number {
        return this._width;
    }
    public set width(value: number) {
        this._width = value;
    }
    public get length(): number {
        return this._length;
    }
    public set length(value: number) {
        this._length = value;
    }
    getInfo(): string {
        return super.getInfo() + `, width=${this._width}, length=${this._length}`;
    }
}
import { Shape } from './Shape';
import { Circle } from './Circle';
import { Rectangle } from './Rectangle';

let myCircle = new Circle(5, 10, 20);
let myRectangle = new Rectangle(0, 0, 3, 7);

// declare an array of shapes ... initially empty
let theShapes: Shape[] = [];

// add the shapes to the array
theShapes.push(myCircle);
theShapes.push(myRectangle);

for (let tempShape of theShapes) {
    console.log(tempShape.getInfo());
    console.log(tempShape.calculateArea());
    console.log();
}
Deiver.js
import { Shape } from './Shape';
import { Circle } from './Circle';
import { Rectangle } from './Rectangle';
let myCircle = new Circle(5, 10, 20);
let myRectangle = new Rectangle(0, 0, 3, 7);
// declare an array of shapes ... initially empty
let theShapes: Shape[] = [];
// add the shapes to the array
theShapes.push(myCircle);
theShapes.push(myRectangle);
for (let tempShape of theShapes) {
    console.log(tempShape.getInfo());
    console.log(tempShape.calculateArea());
    console.log();
}