how to access value of itself object in javascript

1var book  = {}
2
3Object.defineProperties(book,{
4    key1: { value: "it", enumerable: true },
5    key2: {
6        enumerable: true,
7        get: function(){
8            return this.key1 + " works!";
9        }
10    }
11});
12
13console.log(book.key2); //prints "it works!"
14