Question

I’m writing a web application and need to initialize some parameters that I’m pulling via the $.getJSON() method.

$.getJSON("../config/", function(data)
{
     console.debug(data);
}

Now since these values will be used globally throughout the script and will not be triggering an event directly (which is the only implementation of $.getJSON() I could find in the documentation), how can I returning or retrieve this callback data?

Answer 1

Your best bet is to stick with the callback technique.

There are 2 real ways to make it work, both are essentially the same.

$.getJSON("../config/", function(data) {
        SomeObject.config = data; 
        SomeObject.load();   # assuming load tells some-object that it now has data and to get cracking
});

or

$.getJSON("../config/", function(data) {
        SomeObject.load( data );   # SomeObject sets itself up and starts doing its thing
});

Trying to use $.getJSON in a synchronous way ( ie: having it return a value ) will only end in tears and misery for both you and the people using your site, because Synchronous connections have a tendency to block the entire UI. 🙂

As it stands, doing anything like this asynchronously

var i = null;                              #1
$.getJSON("../config/", function(data) {   #2
        i = data;                          #3
});                                        #4
some_function_with(i);                     #5

Will not work, because line 5 is almost guaranteed to execute before line 3.