如何从jQuery中返回的对象中弄清楚

Question

I have this jQuery code:

        $.ajax({
                type: "POST",
                url: "/problems/vote.php",
                dataType: "json",
                data: dataString,
                success: function(data)
                {           
                    // ? :)
                    alert (dataString);


                },
                error : function(data) 
                {
                    alert("ajax error, json: " + data);

                    //for (var i = 0, l = json.length; i < l; ++i) 
                    //{
                    //  alert (json[i]);
                    //}
                }
            });

And when I use it, I get in the alert something cryptic like this: object XMLHTTPReqest

How do I actually get the value that was passed in from the AJAX?

Thanks!

Answer 1

have you tried using the Firefox plugin called FireBug? That's the first place I start as it will show you the exact structure, and data, of the json object returned.

from there it's a simple matter of coding in the object names etc.

Answer 2

In a couple ways:

console.log(data); // allows you to view your object in a tree in the console

or

alert(JSON.stringify(data)); // alerts a serialized string of the object

or in chrome/safari and firefox (firebug) set a break point and check it out.

Answer 3

Firefox - Download Firebug. A must for any web dev.

Chome: instead of alert, do "console.log(data);" This should spit out the object and you can view its properties in the console (hit F12 for that).

Alternatively, write "debugger;" right before your alert and the browser will pause execution. You need to have Firebug running or Chrome Dev Tools open.

Answer 4

First, you're alerting dataString , not anything returned from the server, at least in the success callback. .ajax() callback signatures look like this: success(data, textStatus, jqXHR) , so if you're getting real data back, it can be accessed like any JSON object, via the data parameter. In error it's error(jqXHR, textStatus, errorThrown) , so if that's what you're talking about, it kind of makes sense.

Use Firebug/Chrome/proxy/etc. to make sure what you're getting back from the server is what you expect, or just log it to the console.

Answer 5

I assume you're talking about the error handler.

The signature for the jQuery AJAX error handler is

error(jqXHR, textStatus, errorThrown)

A function to be called if the request fails. The function receives three arguments: The jqXHR (in jQuery 1.4.x, XMLHttpRequest) object, a string describing the type of error that occurred and an optional exception object, if one occurred

You cannot get the "data" returned as there is no data, just an error.