function Vehicle(type) {
  this.type = type;
  this.wheels = 4;
}

Vehicle.prototype.getInfo = function() {
  return `${this.type} with ${this.wheels} wheels`;
};

const car = new Vehicle('sedan');
const bike = Vehicle('motorcycle');

console.log(car.getInfo());
console.log(typeof bike);
console.log(bike?.type || 'undefined');