Summary  
This chapter covers how to modify elements in an array by index, determine an array’s length via its length property, and retrieve the last element by using length – 1.  

General domain of usage  
Data manipulation in applications.

Let's explore how to 
- **Modify array elements**;
- **Find the length of an array**;
- **Access the last element and delve deeper into the concept of indexing**.

## Modifying Array Elements
Array elements can be changed by accessing them through their index and assigning a new value.

const weekdays = ["Monday", "Tuesday", "Wednesday"];
weekdays[0] = "Lunes";
weekdays[1] = "Martes";

console.log(weekdays); // Output: Lunes, Martes, Wednesday

Here, we modify the first two elements of the `weekdays` array to their Spanish translations.

## Array Length
The `length` property of an array represents the number of elements it contains. This property is dynamic and automatically adjusts when elements are added or removed.

const mountains = ["Everest", "K2", "Kangchenjunga", "Lhotse"];

console.log(mountains.length); // Output: 4

In this example, the `mountains` array contains four elements, and `mountains.length` returns `4`.

## Finding the Last Element
To retrieve the value of the last element in an array, we can calculate its index using the array's length. **The index of the last element is always `array.length - 1`.**

const vehicles = ["car", "bike", "bus", "train"];
const lastIndex = vehicles.length - 1;

console.log(vehicles[lastIndex]); // Output: train

In this case, `lastIndex` is computed as `3`, which is the index of the last element, and we access the last element using `vehicles[lastIndex]`.

What is the purpose of the `length` property of an array?

In the example provided below, what is the new value of the first element in the `movies` array after the modification?

How can we access the last element in the `cartoons` array?

What is the value of the `item` in the example provided below?

Learn to work confidently with data in JavaScript by mastering objects and arrays. Understand how to create, access, and manage object properties and methods effectively. Dive into advanced object manipulation techniques, including iteration, cloning, and destructuring for cleaner code. Build a strong foundation in working with arrays and learn to manage, iterate, and modify array elements efficiently. Master advanced array methods like map, filter, find, and sort to transform and handle data effectively in your applications.

Get a clear roadmap of what's to come, understand the prerequisites, and learn valuable tips to set you up for success as you delve into objects, arrays, and essential programming concepts.

Explore the core concepts of JavaScript objects. This section covers the fundamentals of object creation, property management, and method implementation.

Dive into advanced techniques for working with JavaScript objects. This section delves into various strategies to efficiently manipulate and interact with objects.

Embark on a journey into the JavaScript arrays. This section provides a strong foundation for creating arrays, managing elements, and executing basic array operations.

Master the advanced array manipulation skills, covering various techniques and methods for handling arrays effectively in multiple scenarios.

Modifying Arrays and Accessing Elements

Modifying Arrays and Accessing Elements