Access data in a JSON object (parsed) in JavaScript

I need to get the data "messages" from this JSON object. How can I do it in JavaScript?

To access for example the lastname I just use:

response[i].user.lastname

But how can I access the messages?

[
    {
        "user": {
   开发者_高级运维         "last_message": {
                "message": {
                    "created_at": "2011-04-16T16:40:56Z",
                    "updated_at": "2011-04-16T16:40:56Z",
                    "to": null,
                    "id": 10,
                    "user_id": 28,
                    "message": "This is a message"
                }
            },
            "nickname": "thenicky",
            "id": 28,
            "lastname": "white",
            "firstname": "Sean",
            "bio": "A short bio",
            "email": "the@email.com"
        }
    }
]

response[i].user.last_message.message.created_at

And here's a live demo.

response[i].user.last_message.message

Some examples:

alert(response[0].user.last_message.message.id);    
alert(response[0].user.nickname);    
alert(response[0].user.lstname); 

and working code:

JSFiddle Working Example