Callback Best Practices: Callback Discipline

Now that we’ve met our first example of callback hell, we know what we should definitely avoid; however, that’s not the only concern when writing asynchronous code. In fact, there are several situations where controlling the flow of a set of asynchronous tasks requires the use of specific patterns and techniques, especially if we’re only using plain JavaScript without the aid of any external library. For example, iterating over a collection by applying an asynchronous operation in sequence is not as easy as invoking the forEach() function over an array; it actually requires a technique similar to recursion.

In this section, we’ll learn not only about how to avoid callback hell but also how to implement some of the most common control flow patterns, using only simple and plain JavaScript. ...