Higher Order Functions

As we learned in the first topic, a higher order function is a function that either takes another function in as an input argument or returns another function as the return value. Nearly all asynchronous code in JavaScript makes use of higher order functions by passing callback functions in as input arguments. Aside from their prolific use in JavaScript, higher order functions are a key part of Functional Programming and are used for three key benefits: abstraction, utilities, and complexity reduction.

Higher order functions are very important for abstraction. Abstraction is a way to hide the internal workings or details of a procedure. For example, consider the process of cooking a meal from a recipe. A recipe may require you to chop a food item. What is chopping? It is an abstraction of an action. The action and steps to complete the action are to take a knife, place it over the food item, and press downward. Then, move the knife a short distance along the food item...