defineProperty.js

// Wriatble Demo

var obj = { };

Object.defineProperty(obj, "property1", {
    value: "foo",
    writable:true,
    enumerable:true,
    configurable:true
});


Object.defineProperty(obj, "property1", {
    writable:false
});


// Enumerable Demo
for (key in obj){
	console.log(key);
}

Object.defineProperty(obj, "property1", {
    enumerable:false
});

for (key in obj){
	console.log(key);
}

// Configurable Demo
Object.defineProperty(obj, "property1", {
   writable:true
});

Object.defineProperty(obj, "property1", {
   configurable:false
});

Object.defineProperty(obj, "property1", {
   writable:false
});


var person = {
  firstName: "John",
  lastName: "Stone"
}

Object.defineProperty(person, 'fullName', {
  get: function () {
    return this.firstName + ' ' + this.lastName;
  },
  set: function (value) {
    var splitString = value.trim().split(' ');
    
    this.firstName = splitString[0];
    this.lastName = splitString[1];
    }
});

console.log(person.fullName); // "John Stone"
person.fullName = "David Schwimmer";
console.log(person); // {firstName: "David", lastName: "Schwimmer"}