Mastering JavaScript Functional Programming

Memoizing

Back in Chapter 4, Behaving Properly - Pure Functions, we considered the case of the Fibonacci function and saw how we could transform it, by hand, into a much more efficient version by means of memoization: caching calculated values, to avoid recalculations. For simplicity, let's now only consider functions with a single, non-structured parameter, and leave for later functions with more complex parameters (objects, arrays) or more than one parameter for later.

The kind of values we can handle with ease are JS's primitive values: data that isn't objects and has no methods. JS has six of these: boolean, null, number, string, symbol, and undefined. It's likely we would only see the first four as actual arguments. See more in https://developer.mozilla.org/en-US/docs/Glossary/Primitive ...