Parallel, sequential ajax requests

gistfile1.js

function Parallel(oncomplete){
	return {
		'__requests__': [],
		'__responses__': [],
		'__completed__': 0,
		'ajax': function(ajax_props) {
			var self = this,
				complete = $.isFunction(ajax_props.complete) ? ajax_props.complete : function() {},
				success = $.isFunction(ajax_props.success) ? ajax_props.success : function() {},
				count = this.__requests__.length;
			
			ajax_props.complete = function() {
				complete.apply(this, arguments);
				
				self.__completed__++;
				
				if (self.__completed__ == self.__requests__.length) {
					oncomplete.apply(self, (function() {
						var r = [[]];
						
						self.__responses__.sort(function(a,b) {
							return a.index - b.index;
						});
						
						for (var i=0; i < self.__responses__.length; i++) {
							r[0].push(self.__responses__[i].response);
						};
						
						return r;
					})());
				}
				
			};
			
			ajax_props.success = function(response) {
				success.apply(this, arguments);

				var index = ajax_props.index != null ? ajax_props.index : count;

				self.__responses__.push({
					index: index,
					response: response,
					data: ajax_props.data || null
				});
			};			
			
			var req = $.ajax(ajax_props);
			
			this.__requests__.push(req);
			
		}
	};
};

var fb_records = Parallel(function(data) {
	console.dir(data);
	var all_data = (function() {
		var r = [];
		$.each(data,function(a,b) {
			r = r.concat(this);
		});
		return r;
	})();
	console.info(all_data);
});


// ===========
// = Example =
// ===========
test(10);

test(0);

test(40);

function test(offset){
	fb_records
		.ajax({
			'index': offset,
			'url': '/lists/',
			'data': { response: 'json', offset: offset },
			'complete': function(a){
				console.log('complete', offset);
			},
			'success': function(response){
				console.log('response', offset, response);
			}
		});
}

When calling the ajax function (example on line 80) you can specify an index property, which specifies the order of the data responses in the callback function (line 55).