TypeError 'undefined' is not an object in Javascript / Jquery JSON parser

Question

Javascript/JQuery noob here, so apologies.

I'm using .ajax to get a JSON object then the code below to loop through and append the fields to the page. Easy.

$.each(data, function(i, item) {
    $("#div-ipos").append(
        "<img src=" + item.user.avatar_small_url + ">&nbsp;"
        + item.user.first_name 
        + "<hr /><br />"
    );
});

It works and the output is as expected, complete with the avatar path passed into an <img> tag.

However I get the following error:

TypeError: 'undefined' is not an object (evaluating 'item.user.avatar_small_url')

What do I need to do to that variable to make it behave properly in this context?

Use item.user instead of item.sender? The latter seems to be undefined. — Frédéric Hamidi
– Frédéric Hamidi, Commented May 4, 2012 at 19:55
@FrédéricHamidi Apologies - corrected, was using wrong copy/paste. Please ignore! :) — a_good_swan
– a_good_swan, Commented May 4, 2012 at 19:59
Are some of the items in your JSON object missing their user property? In that case, you will have to test for that situation in your loop. — Frédéric Hamidi
– Frédéric Hamidi, Commented May 4, 2012 at 20:05
Have you tried console.log( item )? It should give you the exact hierarchy of the object. — Matthew Blancarte
– Matthew Blancarte, Commented May 4, 2012 at 20:05
Ok, weirdly now I'm getting 'cant find variable item' in console, but also OPTIONS [path to JSON] resource failed to load - yet I can get the path just fine using CURL and see the JSON returned! ARRRGH! — a_good_swan
– a_good_swan, Commented May 5, 2012 at 10:51

Paul · Accepted Answer · 2012-05-04 20:07:08Z

2

Use console.log(data); before your $.each to check what's in it. Most likely the server response contains an extra array element with no user. So the JSON could look like:

[{"user":{"avatar_small_url":"foo","first_name":"bar"}},
 {"user":{"avatar_small_url":"bar","first_name":"foo"}},
 {"something_other_than_user":9000}]

See how the last array element doesn't have a "user". If you have access to the server code, you may want to modify it so there is always a user, or you may modify your Javascript so that it exits early if the user field doesn't exist with something like: if(typeof item.user == 'undefined') return;

answered May 4, 2012 at 20:07

Paul

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8 Comments

a_good_swan Over a year ago

This is the case - both are within 'user' within 'item', but there are other fields at the next level up, not within 'user'. How does this affect item.user.avatar_small_url though?

Paul Over a year ago

@evilswan What does console.log(data); output?

a_good_swan Over a year ago

says: "ReferenceError: Can't find variable: data"

Paul Over a year ago

@evilswan Is that after the fix on the server-side?

Paul Over a year ago

@evilswan It would be really helpfully to see the json returned from your server. If it's small post it here, if it's huge try making a pastebin: pastebin.com and linking me to it.

|

Jack · Accepted Answer · 2012-05-04 20:01:00Z

0

Sounds like either item.user is not defined, or item is not defined. Have you checked the value of item? I think you are expecting it to be something that it is not.

answered May 4, 2012 at 20:01

Jack

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2 Comments

Jack Over a year ago

Oh I know how each works, but you need to check the value of item to make sure you know what the value of it is. Clearly this is a mismatch between what you are expecting and what you are getting.

a_good_swan Over a year ago

How can I output the contents of 'item' to the console to check?

eugen · Accepted Answer · 2014-12-18 07:42:36Z

0

before fetching check using if condition whether key is present in that array as below

if( key in User)
{
    User[key]
}

edited Dec 18, 2014 at 7:42

eugen

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answered Dec 18, 2014 at 7:23

viswa

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