How to deep copy an object in javascript as object not as array

Question

How to deep copy an object in javascript as object not as array

var x = {attr1: "value", attr2: "value"};
var y = $.extend(true, [], x);
var z = $.extend(true, [], x);

alert($.type(x)); // object
alert($.type(y)); // array [ why not object too ]
alert($.type(z)); // array [ why not object too ]

Answer 1

Instead of

var y = $.extend(true, [], x);

Try

var y = $.extend(true, {}, x);
                       ^^--------- Empty object instead of empty Array