Testing asynchs functionality

asyncjs

function async1(cb,err) {
	setTimeout(function () {
		console.log(1);
		cb();
	}, 1000);
}

function async2(cb,err) {
	setTimeout(function () {
		cb(new Error());
	}, 1000);
}

function async3(cb,err) {
	setTimeout(function () {
		console.log(3);
		cb();
	}, 1000);
}

async.series([
	async1,
	async2,
	async3
], function  (err) {
	console.log(err);
});