Node.js Design Patterns - Fourth Edition

4

Asynchronous Control Flow Patterns with Callbacks

Transitioning from a synchronous programming style to a platform like Node.js, where continuation-passing style (CPS) and asynchronous APIs are the standard, can be challenging. Asynchronous code makes it difficult to predict the order in which statements will execute. Simple tasks such as iterating through a set of files, executing tasks sequentially, or waiting for multiple operations to complete require developers to adopt new approaches and techniques to avoid writing inefficient and hard-to-read code.

When using callbacks to handle asynchronous control flow, the most common mistake is to fall into the trap of “callback hell,” where code grows horizontally with excessive nesting, making ...