polymorphism and inheritance

var person = function (firstName, age) {
  this.name = firstName
  this.age = age
}

person.prototype.getInfo = function () {
  console.log(this.name + ' is ' + this.age + ' years old!')
}

var employee = function (firstName, age, salary) {
  person.call(this, firstName, age)
  this.salary = salary
}

employee.prototype = Object.create(person.prototype)
employee.prototype.constructor = employee

employee.prototype.getInfo = function () {
  console.log(this.name + ' is ' + this.age + ' years old and the salary is ' + this.salary)
}

var p1 = new person('abc', 12)
var e1 = new employee('def', 24, 12000)

p1.getInfo()
e1.getInfo()