为什么在使用extjs ajax时出现JSON字符串解码错误？

Question

Below is my code..

Ext.Ajax.request({
            url:'test.jsp',
            params:{id:id,password:password},
            success:function(response){
                 console.log(response);
                 var results = Ext.util.JSON.decode(response.responseText);                     
                if(results.success){
                    document.location.href="../home.jsp";
                }
            }
        })  

I got an error saying:

Uncaught Error: You're trying to decode an invalid JSON String:

and console.log show

Object {request: Object, requestId: 1, status: 200, statusText: "OK", responseText: "↵↵↵↵↵"…}

If I change code to (I am using url to pass my parameters):

Ext.Ajax.request({
            url:'test.jsp?id=' + id + '&password=' + password,
            success:function(response){
                 console.log(response);
                 var results = Ext.util.JSON.decode(response.responseText);                     
                if(results.success){
                    document.location.href="../home.jsp";
                }
            }
        })  

console.log will show

Object {request: Object, requestId: 1, status: 200, statusText: "OK", responseText: "{success:true,msg:'success',url:'../main.jsp'}↵↵↵↵↵"…}

and everything works.

Why does this happen?

Answer 1

you might pass true to the second params, to make it savemode.

// your code should like:
Ext.util.JSON.decode(response.responseText, true);

it wouldnt solve your problem, but remove the errors.
you still need to check your json, make sure its valid.

Answer 2

An empty string isn't valid JSON. You can run JSON.parse('') and it will throw an exception.

If you run JSON.parse('{}') then it's ok.