Learning Node.js for .NET Developers

Chapter 8. Mastering Asynchronicity

Our JavaScript primer (Chapter 3, A JavaScript Primer) covered all the important concepts to let us start building our application. But there is one fundamental aspect of JavaScript programming worth exploring in more detail: asynchronicity.

Chapter 1, Why Node.js?, discussed the asynchronous programming model of Node.js. It described the consistent approach used throughout Node.js APIs and third-party libraries. Recall that each asynchronous method takes a callback function that gets passed error and result arguments, for example, the fs.stat function we saw in Chapter 1, Why Node.js?:

fs.stat('/hello/world', function (error, stats) {
  console.log('File last updated at: ' + stats.mtime);
});

However, the callback ...