juxt

Takes several functions as argument and returns a function that is the juxtaposition of those functions.

Use Array.prototype.map() to return a fn that can take a variable number of args. When fn is called, return an array containing the result of applying each fn to the args.

const juxt =
  (...fns) =>
  (...args) =>
    [...fns].map((fn) => [...args].map(fn));

juxt(
  (x) => x + 1,
  (x) => x - 1,
  (x) => x * 10
)(1, 2, 3); // [[2,3,4],[0,1,2],[10,20,30]]

juxt(
  (s) => s.length,
  (s) => s.split(" ").join("-")
)("30 seconds of code"); // [[18],['30-seconds-of-code']]