Javascript Array sortByID()

var library = [ //w  w w  .j  av  a 2s  . c  o m
   {
       title:  'The Road Ahead',
       author: 'Bill Gates',
       libraryID: 1254
   },
   {
       title: 'Walter Isaacson',
       author: 'Steve Jobs',
       libraryID: 4264
   },
   {
       title: 'Mockingjay: The Final Book of The Hunger Games',
       author: 'Suzanne Collins',
       libraryID: 3245
   }];

Array.prototype.sortByID = function() {
 return this.sort(function (a,b) {
  return b.libraryID- a.libraryID;
 })
};
console.log(library.sortByID());