JSON undefined error using JQuery

Question

My Javascript alert's undefined when trying to read the following JSON string:

[
    {
        "number_messages":"3"
    },
    {
        "message1":"abc"
    },
    {
        "message2":"c"
    },
    {
        "message3":"a"
    }
]

I am using AJAX to get this string (it gets trough correctly.

resp=jQuery.parseJSON(response);
alert( resp.number_messages );

My ajax call is:

$.ajax({  
type: 'POST',  
url: 'backend2.php',  
data: dataString,
success: submitFinished,
dataType: 'json'
});

This alerts "undefined", no errors show up in dragonfly (it's like firebug but for opera).

I am quite new to the whole JSON JQuery thing, so it's prob. something really easy, but I can't seem to figure it out. I've searched for answers and edited my code for over an hour, and still haven't got it to work.

Where's response coming from? Chances are it doesn't contain the JSON string, but a response object. — Jonathan M
– Jonathan M, Commented Dec 9, 2011 at 22:43

Jake Feasel · Accepted Answer · 2011-12-09 22:42:01Z

3

Try this:

alert( resp[0].number_messages );

answered Dec 9, 2011 at 22:42

Jake Feasel

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2 Comments

Jake Feasel Over a year ago

You do see why that worked, right? It's because you have an array of structures (so you'll have to address each of the other elements with the appropriate index).

Boelensman1 Over a year ago

Yes, it's all clear now. Had been trying with .each because I figured it might be an array but didn't get it to work.

user400654 · Accepted Answer · 2011-12-09 22:42:36Z

0

jQuery automatically parses json data into an object, you dont need jQuery.parseJSON(response)

$.ajax({
  "url":"page.php",
  "dataType":"json",
  "success":function(data){
    alert(data[0].number_messages);
  }
});

answered Dec 9, 2011 at 22:42

user400654

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