JQuery Ajax call as function and invoke the function

index.js

jQuery.extend({
    userCount: function() {
        var result = null;
        $.ajax({
            url:"yourURL.asp?param1="+val1+"&param2="+val1=2,
            type: 'get',
            async: false,
            success: function(data) {
                result = data;
            }
        });
    return result;
    }
});

//Later call the function 
if($.isFunction($.userCount) && $.userCount() == 1) //checking wether the function exist and comparing function return. 
{
  //your code here
}