Mastering JavaScript Functional Programming - Second Edition

Producing an even better solution

In one of the previous solutions, we mentioned that it would be a good idea to do something every time after the first click, and not silently ignore the user's clicks. We'll write a new higher-order function that takes a second parameter—a function to be called every time from the second call onward. Our new function will be called onceAndAfter() and can be written as follows:

const onceAndAfter = (f, g) => {  let done = false;  return (...args) => {    if (!done) {      done = true;      f(...args);    } else {      g(...args);    }  };};

We have ventured further in higher-order functions; onceAndAfter() takes two functions as parameters and produces a third one, which includes the other two within.

You could make onceAndAfter() ...