# Day 7: Working with Objects in JavaScript

Screenshot :-

![](https://cdn.hashnode.com/res/hashnode/image/upload/v1721404193989/f9e1e652-5697-4dfb-a74a-d1f458cbd67b.png align="center")

  
Objects are essential in JavaScript, providing a way to store related data and functionality. This article will guide you through creating and manipulating objects, adding methods, working with nested objects, and iterating over object properties.

## Activity 1: Object Creation and Access

### Introduction

In JavaScript, objects are a fundamental aspect that allow you to store multiple values as properties and methods. They provide a way to group related data and functionalities together, making your code more modular and easier to manage. Today, we will explore creating and manipulating objects, adding methods, working with nested objects, and iterating over object properties.

### Activity 1: Object Creation and Access

Let's start by creating a simple object representing a book and accessing its properties.

```javascript
const book = {
  title: "The Catcher in the Rye",
  author: "J.D. Salinger",
  year: 1951,
};

console.log(book); // Logs the entire book object
console.log(book.title); // Logs the title of the book
console.log(book.author); // Logs the author of the book
console.log(book.year); // Logs the year the book was published
```

In this example, we created a `book` object with three properties: `title`, `author`, and `year`. Each property holds a value related to the book.

### Activity 2: Object Methods

Objects can also have methods, which are functions that operate on the object’s properties.

```javascript
book.getDetails = function () {
  return `${this.title} written by ${this.author}`;
};

console.log(book.getDetails()); // Logs "The Catcher in the Rye written by J.D. Salinger"

book.updateYear = function (year) {
  this.year = year;
  console.log(`The year has been updated to ${this.year}`);
};

book.updateYear(1981); // Updates the year to 1981 and logs "The year has been updated to 1981"
```

Here, we added two methods to the `book` object:

* `getDetails`: Returns a string with the book's title and author.
    
* `updateYear`: Updates the book's year property to a new value and logs the updated year.
    

### Activity 3: Nested Objects

Next, we'll create a `library` object that contains an array of book objects.

```javascript
const library = {
  name: "City Library",
  books: [
    { title: "To Kill a Mockingbird", author: "Harper Lee", year: 1960 },
    { title: "1984", author: "George Orwell", year: 1949 },
    { title: "The Great Gatsby", author: "F. Scott Fitzgerald", year: 1925 },
  ],
};

console.log(library); // Logs the entire library object
console.log(library.name); // Logs the name of the library

library.books.forEach((book) => {
  console.log(book.title); // Logs the title of each book in the library
});
```

The `library` object has a `name` property and a `books` property, which is an array of book objects. We used `forEach` to iterate over the `books` array and log the title of each book.

### Activity 4: The `this` Keyword

We can add methods to each book in the `library` object that use the `this` keyword to reference properties of the book.

```javascript
library.books.forEach((book) => {
  book.getSummary = function () {
    return `${this.title} was published in ${this.year}`;
  };
});

library.books.forEach((book) => {
  console.log(book.getSummary()); // Logs a summary for each book
});
```

In this example, we added a `getSummary` method to each book object in the `books` array, which returns a summary string using the book's title and year.

### Activity 5: Object Iteration

Finally, let's explore different ways to iterate over the properties of an object.

```javascript
for (let key in book) {
  console.log(`${key}: ${book[key]}`); // Logs each property and its value
}

console.log(Object.keys(book)); // Logs an array of the book object's keys
console.log(Object.values(book)); // Logs an array of the book object's values
```

We used a `for...in` loop to iterate over the properties of the `book` object, logging each key and its corresponding value. Additionally, we used `Object.keys` and `Object.values` to log arrays of the object's keys and values, respectively.