Prototype constructor in javascript / node.js

A.js

//node A.js > output.txt

// If Rabbit had any custom properties on it 
// (or static properties as some call it), they would not be copied, you'd have to do that manually using getOwnPropertyNames
// ref: https://stackoverflow.com/a/9267343/1084917
// See https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/getOwnPropertyNames
//        var oldProto = Rabbit.prototype;
//        Rabbit = function() {...};
//        Rabbit.prototype = oldProto;

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

  print() {
    console.log(this.name);
    return this.name;
  }
}

const a = new A('Gaurav');
a.print();

// override constructor
const oldProto = A.prototype;
A = function (name) {
  this.name = 'Hello ' + name;
};
A.prototype = oldProto;

const b = new A('Mehul');
b.print();

output.txt

Gaurav
Hello Mehul