ES6 Person class

gistfile1.txt

var Person = (function(){
  
  var population = 0;
  var privateData = new WeakMap();
  
  class Person {
    constructor(opts) {

      privateData.set(this, {
        dob: opts.dob,
      });

      this.name = opts.name,

      Object.seal(this);
      Person.incrementPopulation();
    }

    //Public
    greet() {
      console.log('Hello my name is ' + this.name +
          ' and I am ' + this.age + ' years old');
    };
    
    get age() {
      return new Date().getFullYear() - privateData.get(this).dob.getFullYear();
    };
    
    static getPopulation() {
      return population;
    };
    
    static incrementPopulation() {
      population++;
    };
  };
  
  return Person;
})();

var andy = new Person({
  name: 'Andy',
  dob: new Date('12/13/1979')
});

Person.population = 200;
console.log(Person.getPopulation());

var dave = new Person({
  name: 'Dave',
  dob: new Date('03/09/1984')
});

console.log(Person.getPopulation());

//andy.dob = new Date('12/13/1990');
//andy.age = 22;
andy.greet();
andy.name = "Andrew";
console.log(andy.name);// = 'Andrew';
//andy.set('name', 'Andrew');
andy.greet();
dave.greet();

It would be nice to do away with the closure around the class, but at the moment that encapsulates the private population variable.