JQuery :: Using Ajax Function To Fetch JSON Into Variable

I'm trying to fetch JSON contents via ajax() from a file using this code:
// grab pages via AJAX request
sm.pages = (function() {
var json = null;
$.ajax({
async: false,
global: false,
url: 'pages.json',
dataType: 'json',
success: function(data){
json = data;
console.log(data);
}});
return json;
})();
One problem though. The success function doesn't seem to be firing at all even though I can see the request was successfully in Firebug.