SOURCE

// var person = {};
// Object.defineProperty(person, "name", {
//     writable: false,
//     configurable: false,
//     value: "wzn"
// });

// console.log(person.name);
// person.name = "123";
// console.log(person.name);
// delete person.name;
// console.log(person.name);

// var book = {
//     _year: 2004,
//     edition: 1
// };
// Object.defineProperty(book, "year", {
//     get: function(){
//         return this._year;
//     },
//     set: function(newYear){
//         if (newYear > 2004){
//             this._year = newYear;
//             this.edition += newYear - 2004;
//         }
//     }
// });
// book.year = 2005;
// console.log(book.edition);

var book2 = {};
Object.defineProperties(book2, {
    _year: {
        writable: true,
        value: 2004
    },
    edition: {
        writable: true,
        value: 2
    },
    year: {
        get: function(){
            return this._year;
        },
        set: function(newValue){
            if (newValue > 2004){
                this._year = newValue;
                this.edition += newValue - 2004;
            }
        }
    }
});
var descriptor = Object.getOwnPropertyDescriptor(book2, "_year");
console.log(descriptor.value);
console.log(descriptor.configurable);
console.log(descriptor.writable);
console.log(typeof descriptor.get);

var descriptor = Object.getOwnPropertyDescriptor(book2, "year");
console.log(descriptor.configurable);
console.log(descriptor.enumerable);
console.log(typeof descriptor.get);