JavaScript : Objects

In JavaScript, objects are a fundamental data type that allows you to store collections of data in key-value pairs. Objects are used to represent real-world entities, and they are versatile and powerful constructs in JavaScript. Here's how you can work with objects in JavaScript:

1. Object Literal:

You can create an object using object literal notation, which consists of key-value pairs enclosed in curly braces {}.

let person = { name: "John", age: 30, isStudent: false };

2. Accessing Object Properties:

You can access properties of an object using dot notation ( . ) or bracket notation ( [] ).

console.log(person.name); // Output: "John" console.log(person["age"]); // Output: 30

3. Adding or Modifying Properties:

You can add new properties or modify existing properties of an object.

person.city = "New York"; // Adding a new property person.age = 35; // Modifying an existing property

4. Nested Objects:

Objects can contain other objects as properties, allowing you to create nested data structures.

let student = { name: "Alice", age: 25, contact: { email: "alice@example.com", phone: "123-456-7890" } };

5. Object Methods:

You can define functions as properties of an object, known as methods.

let car = { brand: "Toyota", model: "Camry", start: function() { console.log("Engine started"); } };

car.start(); // Output: "Engine started"

6. Object Constructor:

You can create objects using constructor functions or the Object constructor.

function Person(name, age) { this.name = name; this.age = age; }

let john = new Person("John", 30);

7. Object Destructuring:

You can extract properties from objects and assign them to variables using object destructuring.

let { name, age } = person; console.log(name); // Output: "John" console.log(age); // Output: 30

8. Object Iteration:

You can iterate over the properties of an object using for...in loop or Object.keys() method.

for (let key in person) { console.log(key + ": " + person[key]); }

Example Usage:

Here's an example demonstrating various operations with objects in JavaScript:

let person = { name: "John", age: 30, isStudent: false };

console.log(person.name); // Accessing property person.city = "New York"; // Adding property console.log(person.city); // Output: "New York"