node.js
async in Node
JavaScript callbacks are not readable when nested in many layers. Async [https://www.npmjs.com/package/async] library is a great tool to overcome this. I find a good tutorial [http://www.sebastianseilund.com/nodejs-async-in-practice] with case examples written by Sebastian Seilund. Introduced control flows are: * async.parallel([taskFunctions], finalCallback)