Learning Node.js: A Hands-On Guide to Building Web Applications in JavaScript

3. Asynchronous Programming

Now that you have a refreshed and updated idea of what JavaScript programming is really like, it’s time to get into the core concept that makes Node.js what it is: that of nonblocking IO and asynchronous programming. It carries with it some huge advantages and benefits, which you shall soon see, but it also brings some complications and challenges with it.

The Old Way of Doing Things

In the olden days (2008 or so), when you sat down to write an application and needed to load in a file, you would write something like the following (let’s assume you’re using something vaguely PHP-ish for example purposes):

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$file = fopen('info.txt', 'r');// wait until file is open$contents = fread($file, ...