JS - Using the defineProperty() option available in EcmaScript 5

defineproperties

//Example 1

var createPerson = function(firstName, lastName){
  var person = {};

  //Descriptor object - define single property
  //2 types - Data & Accessor descriptors

  Object.defineProperty(person, "firstName", {

    //data descriptor
    //immutable unless you set the writable descriptor

    value: firstName
  });
  
  Object.defineProperty(person, "lastName", {
    value: lastName
  });
 

  return person;
};

var person = createPerson("Jack", "Foo");

/**************************************************************************/
//Example 2 

var createPerson = function(firstName, lastName){
  var person = {};

  //Define multiple properties
  Object.defineProperties(person, {
    firstName : {
      value: firstName,
      writable: true
    },
    lastName : {
      value: lastName,
      writable: true
    },
    //Accessor descriptors
    fullName: {
      get:  function() {return this.firstName + " " + this.lastName; 
      },
      set:  function(value) {
        this.firstName = value; 
        this.lastName = value;
      }
    }
  });
  
  
  return person;
};

var person = createPerson("Jack", "Foo");

/***************************************************************************
Example 3
*/

 var createPerson = function(firstName, lastName){
  var person = {};
   
//Using the configurable option
   //leaves object open for altering - not optimal
  Object.defineProperties(person, {
    firstName : {
      value: firstName
    },
    lastName : {
      value: lastName
    },
    //Accessor descriptors
    fullName: {
      get:  function() {return this.firstName + " " + this.lastName; 
      },
      configurable: true
    }
  });
  
  
  return person;
};

var person = createPerson("Jack", "Foo");

Object.defineProperty(person, "fullName", {
  get: function(){return this.lastName + ", " +this.firstName;}
});

/*****************************************************************************
Example 4
*/

 var createPerson = function(firstName, lastName){
  var person = {};
   
//Using the enumerable option
   
  Object.defineProperties(person, {
    firstName : {
      value: firstName,
      enumerable : true
    },
    lastName : {
      value: lastName,
      enumerable : true
    },
    //Accessor descriptors
    fullName: {
      get:  function() {return this.firstName + " " + this.lastName; 
      },
      enumerable : true
    }
  });
  
  
  return person;
};

var person = createPerson("Jack", "Foo");