JavaScript for Line of Business Applications

When discussing functional programming we often talk about the machinery, and not the core principles. Functional programming is not about monads, monoids, or zippers. It is primarily about writing programs by composing generic reusable functions. This article is about applying functional thinking when refactoring JavaScript code.

n general, applicative programming is the pattern of defining a function that takes a function and then invokes that function for each element in a collection/list. To apply this definition of applicative programming to JavaScript, you will need to know a little something about first-class functions before we dive in. So, let's start there.

JavaScript has first class functions. This means that instances of the Function constructor can go and do anything any value in the language can do because functions in JavaScript are values.

Unless you've used a functional programming language such as ML or Haskell, concepts such as partial application and currying may be foreign to you. Since JavaScript supports first-class functions, once you understand these concepts, you can put them to use in your code.

Whether writing code just for yourself or presenting an API to your users, it's often helpful to create a more specialized function as a "wrapper" to a more generalized function if you expect to be performing a task repetitively. One way to do this would be to just define the functions manually.