What is the function of `map()` in JavaScript?

The function of map() in JavaScript is to create a new array by applying a specified transformation function to each element of an existing array. This means that for every element in the original array, map() executes the provided callback function and constructs a new array populated with the results of these function calls.

Using map() does not alter the original array; instead, it returns a new array that reflects those transformations, allowing for functional programming practices where immutability of data is preferred. For example, if you have an array of numbers and want to create a new array that contains the squares of those numbers, map() would apply the squaring function to each number and return the resulting array.

This contrasts with other methods such as sorting or filtering, which have different purposes in array manipulation. Sorting would rearrange the elements based on specified criteria, while filtering would retain only those elements that meet certain conditions. Therefore, the defining feature of map() is its ability to transform elements and produce a new array without modifying the original data structure.