Mapping String Characters in JavaScript

Introduction

In this lab, we will explore the mapString function in JavaScript. This function allows us to create a new string by applying a provided function to every character in a given string. We'll learn how to use String.prototype.split(), Array.prototype.map(), and Array.prototype.join() to implement mapString and see how it can be useful in various scenarios.

Skills Graph

Function to Map Characters in a String

To use this function to map characters in a string, follow these steps:

• Open the Terminal/SSH and type node to start practicing coding.
• Use String.prototype.split() and Array.prototype.map() to call the provided function, fn, for each character in the given string.
• Use Array.prototype.join() to recombine the array of characters into a new string.
• The callback function, fn, takes three arguments: the current character, the index of the current character, and the string mapString was called upon.

Here's the function code:

const mapString = (str, fn) =>
  str
    .split("")
    .map((c, i) => fn(c, i, str))
    .join("");

Example usage:

mapString("lorem ipsum", (c) => c.toUpperCase()); // 'LOREM IPSUM'

Summary

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