# Introduction In this lab, we will work on a JavaScript programming exercise that involves replacing or appending values in an array based on a comparison function. Through this exercise, you will learn how to use the spread operator, `Array.prototype.findIndex()`, `Array.prototype.push()`, and `Array.prototype.splice()` to manipulate arrays in JavaScript. This lab will help you improve your skills in working with arrays and functions in JavaScript.
Click the virtual machine below to start practicing