如何在jQuery Ajax成功回调中处理我的JSON数据？

$.ajax({
  url: url,
  dataType: \'json\',
  data: data,
  success: function(json_data){
    //What\'s the efficient way to extract the JSON data and get the value
  }
});

{\"contact\":[{\"address\":[{\"city\":\"Shanghai\",\"street\":\"Long
            Hua Street\"},{\"city\":\"Shanghai\",\"street\":\"Dong Quan
            Street\"}],\"id\":\"huangyim\",\"name\":\"Huang Yi Ming\"}]}

var name = json_data.contact[0].name;
var addresses = json_data.contact[0].address;

for(var i = addresses.length; i--;) {
    var address = addresses[i];
    // address.city
    // address.street
    // etc
}