Map

map() is a built-in method for arrays that acts like a transformation machine. It iterates through each element in the array and applies a function you define (the callback function) to each element. This function can modify, transform, or create something entirely new based on the original element. The result of these transformations is then used to populate a brand new array.

Imagine you have a list of product prices (numbers) and you want to create a new list showing discounted prices (transformed elements). Here's how map() comes into play:

const prices = [10, 15, 20, 25];

// Callback function to apply a 10% discount
const discountedPrices = prices.map(price => price * 0.9);

console.log(discountedPrices); // Output: [9, 13.5, 18, 22.5]

In the above example, it uses map() to create a new array discountedPrices containing prices with a 10% discount. The map() method iterates through prices and applies the discount calculation (price * 0.9) to each item, resulting in the discounted prices in the new array.