javascript global var from ajax function

Question

I'm using dajaxice to retrieve a json attribute - that I would like to be global. I'm not sure why my global var is always "undefined":

var recent_id;
$(function(){
    recent_id = Dajaxice.ticker.get_home_timeline(get_home_timeline_callback);
        alert(recent_id);
    });

function get_home_timeline_callback(data){
    if(data==Dajaxice.EXCEPTION){
        alert('Error! Something happens!');
    }else{
          var parsed = JSON.parse(data.home_timeline);
          var parsed_id = {'parsed_id':parsed[0].id_str};
          console.log(parsed_id);
    }
    return parsed_id;    
}

@dajaxice_register
def get_home_timeline(request):
    home_timeline = oauth_req(
    'http://api.twitter.com/1/statuses/home_timeline.json?count=1',
    settings.TWITTER_TOKEN_KEY,
    settings.TWITTER_TOKEN_SECRET
    )
    return simplejson.dumps({'home_timeline': home_timeline })

Is this a bad way to access a var to be used in another ajax function?

Is your ajax asynchronous? Do you know what that means? – jfriend00 Jan 10 '12 at 04:17 — jfriend00, Jan 10 '12 at 04:17

score 0 · Answer 1 · answered Jan 10 '12 at 05:12

Seems like async issue. Modify your get_home_timeline_callback function as following

function get_home_timeline_callback(data){
    if(data==Dajaxice.EXCEPTION){
        alert('Error! Something happens!');
    }else{
          var parsed = JSON.parse(data.home_timeline);
          var parsed_id = {'parsed_id':parsed[0].id_str};
          console.log(parsed_id);
    }
    //debug
    alert(parsed_id);
    //since the value has come, now assign it to the global variable
    recent_id = parsed_id;    
}

I already tried that and when the global var recent_id is accessed out of the get_home_timeline() function scope it is still undefined. — neridaj, Jan 10 '12 at 20:37

score 0 · Answer 2 · edited May 23 '17 at 12:03

It seems like the variable scope issue. The scope of the variable parsed_id is declared within the else statement within the { }, so its scope is within the else statement. And when you return the parsed_id outside the brackets it might be giving undefined.

Go through the scope of variables explanation here

Change your function as shown below.

function get_home_timeline_callback(data)
{
    var parsed_id = "";
        if(data==Dajaxice.EXCEPTION)
        {
            alert('Error! Something happens!');
        }
        else
        {
              var parsed = JSON.parse(data.home_timeline);
              parsed_id = {'parsed_id':parsed[0].id_str};
              console.log(parsed_id);

        }
        return parsed_id;
}

Now here the scope of the variable parsed_id can be accessed anywhere within function. Hope this solves your problem if not sorry. This was my assumption that the scope might be affected.

javascript global var from ajax function

2 Answers2