Parsing JSON object changes order - php

Question

For some odd reason, when I parse my JSON object being send via AJAX, it throws the object out of order.
$.post('get_notes', note_data, function(data){
var notes_obj = $.parseJSON(data);
});
When I console.log data, this is what is returned:
{"502":{"text":"First Response","user_name":"Admin","date":"11-12-2013 9:21"},
"509":{"text":"Second Response","user_name":"Admin","date":"11-12-2013 9:22"},
"508":{"text":"Third Response","user_name":"Admin","date":"11-12-2013 9:24"},
"504":{"text":"Fourth Response","user_name":"Admin","date":"11-12-2013 9:24"}}
This is the correct order. Notice the dates are properly ascending.
When I console.log notes_obj, this is what it returns:
502: Object
504: Object
508: Object
509: Object
For some reason, $.parseJSON() decided to re-order the output by id, and not by date which is what I need.
Any idea why this is happening?

Answer 1

The objects defined by JSON have no order to their properties at all, so it's perfectly acceptable for something to serialize the properties in any order.
The following are exactly identical objects in JSON:
{
"question": "Life, the Universe, and Everything",
"answer": 42
}
{
"answer": 42,
"question": "Life, the Universe, and Everything"
}
In the comments you asked
How do I fix it?
You stop relying on the order of something that is not defined to have any order. You could, for instance, reformat your response so it's an array, because arrays have order:
[
{ "key": "502", "text": "First Response", "user_name": "Admin", "date": "11-12-2013 9:21" },
{ "key": "504", "text": "Fourth Response", "user_name": "Admin", "date": "11-12-2013 9:24" },
{ "key": "508", "text": "Third Response", "user_name": "Admin", "date": "11-12-2013 9:24" },
{ "key": "509", "text": "Second Response", "user_name": "Admin", "date": "11-12-2013 9:22" }
]
Now instead of an object with various keys, you have an array of objects, where each object has a key property (and the other information).