Get the variable of a json request outside the function (jquery) - ajax

Question

I feel pretty stupid asking this but how can I get the variable crdnts outside the function
$(function() {
var coordinates = {
LoadDefault: function() {
$.getJSON('http://api.wipmania.com/jsonp?callback=?', '', function(json) {
var crdnts = json.latitude + "," + json.longitude;
//alert(crdnts);//this works
return crdnts;
});
}
};
alert(coordinates.LoadDefault());//I would like to get the crdnts variable here.
});
or
http://jsfiddle.net/stofke/Lv3YD/

Answer 1

javascript ajax is asynchronous. so you need to use callbacks:
$(function() {
var coordinates = {
LoadDefault: function() {
$.getJSON('http://api.wipmania.com/jsonp?callback=?', '', function(json) {
var crdnts = json.latitude + "," + json.longitude;
call_alert(crdnts); //callback
});
}
};
function call_alert(cr){
alert(cr);
}
coordinates.LoadDefault();
});

Answer 2

You can't. Your Ajax call is asynchronous, so you cannot predict when will it return.
The only thing you can do is doing something with it in the success callback, or set your Ajax to be synchronous if it is a choice (in this case all JS execution will wait until the request is finished).
For example, you can call a function when the Ajax call successfully finished:
$(function() {
var coordinates = {
LoadDefault: function() {
$.getJSON('http://api.wipmania.com/jsonp?callback=?', '', function(json) {
var crdnts = json.latitude + "," + json.longitude;
callSomething(crdnts);
});
}
};
function callSomething(x) {
alert(x);
}
});