The async library
If you take a look for a moment at every control flow pattern we have analyzed so far, you will see that they can be used as a base to build reusable and more generic solutions. For example, we could wrap the unlimited parallel execution algorithm into a function that accepts a list of tasks, runs them in parallel, and invokes the given callback when all of them are complete. This way of wrapping control flow algorithms into reusable functions can lead to a more declarative and expressive way of defining asynchronous control flows, and that's exactly what async (nodejsdp.link/async) does.
The async library (not to be confused with the async/await keywords, which we will discuss later in this book) is a very popular solution, in Node.js and JavaScript in general, for dealing with asynchronous code. It offers a set of functions that greatly simplify the execution of tasks in different configurations, and it also provides useful helpers...
