javascript - jquery.extend(true, [], obj) not creating a deep copy -

jsfiddle here.

if deep copying worked, output "curious george" , not "ender's game". how can make deep copy? answer this question indicates $.extend(true, [], obj) creates deep copy. yet example shows doesn't.

function person(){} person.prototype.favorite_books = [];  var george = new person(); george.favorite_books = ["curious george"];  var kate = new person(); kate.favorite_books = ["the da vinci code", "harry potter"];  var people = [kate, george];  var people_copy = $.extend(true, [], people); people_copy[0].favorite_books[0] = "ender's game";  $('#text').text(people[0].favorite_books[0]); 

solution

i updated jsfiddle. turns out need deep copy each object in array individually if object custom object (that is, $.isplainobject returns false).

and here real answer:

at moment jquery can clone plain javascript objects, while you're using custom ones. , that's obvious, since jquery cannot know how instantiate new custom object. works expected:

var george = {}; george.favorite_books = ["curious george"];  var kate = {}; kate.favorite_books = ["the da vinci code", "harry potter"];  var people = [kate, george];  var people_copy = $.extend(true, [], people);  console.log(people_copy[0].favorite_books == people[0].favorite_books); 

reference jquery code: https://github.com/jquery/jquery/blob/master/src/core.js#l305

see checks if it's jquery.isplainobject(copy) or it's array. otherwise performs reference copy.