mochikit-deferred.js

function main() {
	var d = accessAndShowEntries();
	d.addCallback(function() {
		console.log("finish");
	});
	setTimeout(function() {
		console.log("cancel!");
		d.cancel();
	}, 2500);
}

function accessAndShowEntries() {
	function loop(i) {
		if (i >= 5) return;
		return accessEntry(i).addCallback(function (data) {
			console.log(data);
			return callLater(0, loop, i + 1);
		});
	}
	return callLater(0, loop, 0);
}

// XHR で何かアクセスする代わり
function accessEntry(i) {
	var d = new Deferred();
	var cb = d.callback.bind(d, "foo"+i);
	var timerId = setTimeout(cb, 1000);
	d.canceller = function () {
		clearTimeout(timerId);
	};
	return d;
}