Question

I have 3 json requests which fetch data, i am wanting to store the results and add them together? i have made an attempt but i get NaN as they are getting set as null. What am i doing wrong?

var twitter, facebook, web, total_count;

    // grab from facebook
    var facebook = $.getJSON('https://graph.facebook.com/'+f_page+'?callback=?', function(data) {
        var fb_count = data['likes'].toString();
        fb_count = add_commas(fb_count);
        $('#fb_count').html(fb_count);
    });

    // grab from twitter
    var twitter = $.getJSON('http://api.twitter.com/1/users/show.json?screen_name='+t_page+'&callback=?', function(data) {
        twit_count = data['followers_count'].toString();
        twit_count = add_commas(twit_count);
        $('#twitter_count').html(twit_count);
    });

    // grab from website
    var web = $.getJSON('json.php', function(data) {
        web_count = data['count'].toString();
        web_count = add_commas(web_count);
        $('#website_count').html(web_count);
    });

    $.when(facebook, twitter, web).done( countTotal );

    function countTotal() {
        total_count = facebook + twitter + web;
        total_count = add_commas(total_count);
        $('#count_total').html(total_count);
    }

Answer 1

You are trying to acces data that is asychronously loaded. That means when the program code comes to this line:

total_count = fb_count + twit_count + web_count;

The data isn’t there yet.

You need to wait until the data is ready:

var fb_count, twit_count, web_count, total_count;

var first = $.getJSON( /* code1 */);
var second = $.getJSON( /* code2 */);
var third = $.getJSON( /* code3 */);

$.when(first, second, third).done( doYourMath );

function doYourMath() {
    total_count = fb_count + twit_count + web_count;
    total_count = add_commas(total_count);
    $('#count_total').html(total_count);
}

PS:
Make sure total_count is defined somewhere as variable (var total_count), else it will pollute the global scope.