JSON Object, undefined?

Question

I'm trying to develop a web application using jQuery, AJAX and JSON. I have this code:

console.log(response.s);
if (response.s == true) {
    alert('good');
} else {
    alert('bad');
}

This response (via console.log() on Firebug) seems to be:

{"s":true}

Which seems to be a JSON object right? Well, the line console.log(response.s); on the first code I added here returns undefined. What's the problem?

Can you click the {"s":true} object within Firebug console and see it in object (DOM) explorer or is it written as string in the Firebug console (i.e. not clickable)? — Nikhil
– Nikhil, Commented Mar 18, 2011 at 15:09

Claudiu · Accepted Answer · 2012-12-05 00:13:52Z

8

What is typeof (response)? if it's a string then you have to parse it, first. (You'd be accessing the s field of a string, which doesn't exist, so JavaScript gives you undefined instead of throwing an Exception or whatever.)

edited Dec 5, 2012 at 0:13

answered Mar 18, 2011 at 15:09

Claudiu

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4 Comments

sh03 Over a year ago

How can i check the type of it? How could i parse it?

Claudiu Over a year ago

literally type in typeof (response.s) in the console. or type in response.s.constructor and see what that gives you.

Ruan Mendes Over a year ago

I think you meant to ask about typeof response. If that returns "string", OP needs to call jQuery.parseJSON( response )

sh03 Over a year ago

Yes it was a string. I just added dataType: 'json' to my ajax jQuery request and it worked fine. Thanks.

Coin_op · Accepted Answer · 2011-03-18 15:09:44Z

1

If the content-type of the response isn't application/json then the javascript is probably assuming that it is just a string.

Supplying the correct content header should therefore sort your problem.

Alternatively you could probably use eval() to convert the string into a json object.

answered Mar 18, 2011 at 15:09

Coin_op

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Comments

alexl · Accepted Answer · 2011-03-18 15:10:30Z

1

try to use:

var obj = jQuery.parseJSON(response);
console.log(obj.s);

Hope it helps.

answered Mar 18, 2011 at 15:10

alexl

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