function Vehicle(type, wheelsCount) {  

  if (!(this instanceof Vehicle)) {

    throw Error('Error: Incorrect invocation');

  }

  this.type = type;

  this.wheelsCount = wheelsCount;

  return this;

}

// Constructor invocation

var car = new Vehicle('Car', 4);  

console.log(car.type);               // => 'Car'  

console.log(car.wheelsCount);        // => 4  

console.log(car instanceof Vehicle); // => true

​

// Function invocation. Generates an error.

var brokenCat = Vehicle('Broken Car', 3);