queue.js

function queue() {

	queue.stack = queue.stack || [];
	var push = function(scope, obj) { Array.prototype.push.call(scope, obj); }

	if (arguments.length) {
		queue.stack.push(arguments);
		if (queue.process) return false;
	}
	
	queue.process = function(current) {
		
		push(arguments, function() {

			if (queue.stack.length) {
			    queue();
			} else {
				delete queue.process
			}

		})
		
		queue.job.apply(this, arguments)
	
	};
	
	queue.process.apply(this, queue.stack.shift())
};

queue.job = function(num, next) {
	
	setTimeout(function() {
		console.log(num);
		next();
	}, 500)
	
}

queue(1);
queue(2);
queue(3);