Simplifying JavaScript

Tip 35

Combine Currying and Array Methods for Partial Application

In this tip, you’ll learn to lock in variables with partial application of functions.

In the previous tip, you saw how you can give parameters a single responsibility with higher-order functions and partial application. It solved the problem of having unrelated parameters, but it didn’t solve the problem of using the same parameters over and over. You still passed in the same parameters multiple times.

With higher-order functions, you can avoid repetition by creating a new function with values you lock in once and use later. When you return a higher-order function, you don’t have to invoke it right away. After you invoke it once, you have another pre-made function that you can ...