Summary  
The chapter explains the `map` method, a non-mutating array function that applies a callback to each element and returns a new array of the callback’s results.  

General domain of usage  
Data transformation in arrays.

The `map` method is a powerful tool for transforming arrays in JavaScript. It allows you to create a new array by applying a function to each element of an existing array. The original array remains unchanged, making `map` a non-mutating method.


const numbers = [1, 2, 3, 4];
const doubled = numbers.map(function(number) {
  return number * 2;
});
console.log(doubled); // Output: [2, 4, 6, 8]


When you call `array.map(callback)`, the `callback` function is executed once for every element in the array. The `callback` receives up to three arguments:
- The current element value;
- The current element's index;
- The original array.

Most commonly, you will use only the first parameter—the current value. The function you provide should return a value, which will become the corresponding element in the new array.

This makes `map` ideal for tasks like:
- Converting numbers to strings;
- Modifying each object in an array of objects;
- Extracting a specific property from each object in an array.

Since `map` always returns a new array, you can chain it with other array methods or use it to keep your data transformations clear and predictable.

Explore the core JavaScript concepts you need to start building apps. Learn how to store data, work with functions, handle arrays and objects, and write basic logic. The focus is on practical concepts used in React and React Native. 

Array Methods (map)