Juxtapose Functions in JavaScript

Introduction

In this lab, we will explore the concept of Juxtapose Functions in JavaScript. We will learn how to create a function that takes multiple functions as arguments and returns a new function that applies those functions to the same set of arguments, returning an array of the results. By the end of this lab, you will have a better understanding of how to use Juxtapose Functions to simplify your code and make it more efficient.

Skills Graph

Explanation of Juxtapose Functions

To use the juxt function, first open the Terminal/SSH and type node to start practicing coding. The juxt function takes several functions as arguments and returns a function that is the juxtaposition of those functions.

To create the juxt function, use Array.prototype.map() to return a fn that can take a variable number of args. When fn is called, it should return an array containing the result of applying each fn to the args.

Here's an example implementation of the juxt function:

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

Once you've defined the juxt function, you can use it by passing in any number of functions as arguments, followed by any number of arguments to pass to those functions.

Here are a couple examples of using the juxt function:

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("-")
)("happy coding"); // [[18], ['happy-coding']]

In the first example, the juxt function takes three functions as arguments and returns a new function. When that new function is called with the arguments 1, 2, 3, it applies each of the three functions to those arguments and returns an array of arrays containing the results.

In the second example, the juxt function takes two functions as arguments and returns a new function. When that new function is called with the argument 'happy-coding', it applies each of the two functions to that argument and returns an array of arrays containing the results.

Summary

Congratulations! You have completed the Juxtapose Functions lab. You can practice more labs in LabEx to improve your skills.