sencha touch - ajax request (JSON response)

Hi i am using the following code to send an ajax request in my mobile application

var button = new Ext.Toolbar({
                cls: "top_tool_bar2",
                height: 35,
                items: [this.text,
                        {xtype: 'spacer'}, 
                        {html: new Ext.XTemplate('<img style="width:.5em;height:.5em;" src="resources/imgs/down_arrow.png" />').apply({name: 'down_arrow'}),
                        handler: function () {
                              Ext.Ajax.request({
                                  url: '/RadMobApp/api',
                                   params:{
                                    action:'invokeService',
                                    serviceName: 'prescriptionService',
                                    methodName: 'sampleClinicalInfo',
                                    username: 'superuser',
                                    password: 'superuser'

                                  },
                                  success: function(xhr) {
                                      var response = Ext.decode(xhr.responseText);
                                     // alert(response.diagnosis);
                                  }
                              });
                        }}
                       ]
            });

I am getting an JSON response as like this

[{"systemReviewInfoMapListSize":1,"diagnosis":"Impaired hearing\nEarache \nEar noise","isClinicalSummaryAvail":"false","isSymptom":"true","isDiagnosis":"true","symptom":"Impaired hearing\nEarache \nEa开发者_JAVA百科r noise","isSystemReviewInfo":"true"}] 

how can i read this in my application... Thanks in advance.

---

You can try the following:

var data = Ext.JSON.decode(response.responseText.trim());

Assuming your response comes in as such: "id":123, "name": "Mac Arthur" then you should be able to access them like so:

alert("ID: " + data.id + "; Name:" + data.name);

Hope this helps