constructor

class Polygon {
  constructor() {
    this.name = "Polygon";
  }
}

const poly1 = new Polygon();

console.log(poly1.name);
// Expected output: "Polygon"

constructor() { ... }
constructor(argument0) { ... }
constructor(argument0, argument1) { ... }
constructor(argument0, argument1, ... , argumentN) { ... }

class Person {
  constructor(name) {
    this.name = name;
  }

  introduce() {
    console.log(`Hello, my name is ${this.name}`);
  }
}

const otto = new Person("Otto");

otto.introduce();

constructor() {}

constructor(...args) {
  super(...args);
}

class ValidationError extends Error {
  printCustomerMessage() {
    return `Validation failed :-( (details: ${this.message})`;
  }
}

try {
  throw new ValidationError("Not a valid phone number");
} catch (error) {
  if (error instanceof ValidationError) {
    console.log(error.name); // ValidationError  Error!
    console.log(error.printCustomerMessage());
  } else {
    console.log("Unknown error", error);
    throw error;
  }
}

class ValidationError extends Error {
  constructor(message) {
    super(message); //    
    this.name = "ValidationError";
    this.code = "42";
  }

  printCustomerMessage() {
    return `Validation failed :-( (details: ${this.message}, code: ${this.code})`;
  }
}

try {
  throw new ValidationError("Not a valid phone number");
} catch (error) {
  if (error instanceof ValidationError) {
    console.log(error.name); //  ValidationError!
    console.log(error.printCustomerMessage());
  } else {
    console.log("Unknown error", error);
    throw error;
  }
}

class Square extends Polygon {
  constructor(length) {
    // length         .
    super(length, length);
    // :  , this    super()   .
    //   ReferenceError .
    this.name = "Square";
  }

  get area() {
    return this.height * this.width;
  }

  set area(value) {
    this.height = value ** 0.5;
    this.width = value ** 0.5;
  }
}

class Polygon {
  constructor() {
    this.name = "Polygon";
  }
}

class Square extends Polygon {
  constructor() {
    super();
  }
}

class Rectangle {}

Object.setPrototypeOf(Square.prototype, Rectangle.prototype);

console.log(Object.getPrototypeOf(Square.prototype) === Polygon.prototype); //false
console.log(Object.getPrototypeOf(Square.prototype) === Rectangle.prototype); //true

let newInstance = new Square();
console.log(newInstance.name); //Polygon