JavaScript Objects

• Objects in JavaScript are containers for named values, called properties, and methods (functions).
• Properties and methods are accessed using dot notation (object.property) or bracket notation (object['property']).

Syntax:

// Object Literal Syntax
const person = {
  firstName: 'John',
  lastName: 'Doe',
  age: 30,
  greet: function() {
    console.log('Hello!');
  }
};

• firstName, lastName, age: Properties of the object.
• greet: A method (function) within the object.

Why it is Used:

• Data Organization: Objects help organize and structure data by grouping related information.
• Code Reusability: Methods within objects allow for the encapsulation of functionality for reuse.
• Real-world Representation: Objects can model real-world entities and their interactions.

Accessing Properties and Methods:

// Accessing Properties and Calling a Method
console.log(person.firstName); // Output: John
console.log(person['lastName']); // Output: Doe
person.greet(); // Output: Hello!

Adding and Modifying Properties:

// Adding a New Property
person.gender = 'Male';

// Modifying an Existing Property
person.age = 31;

Object Methods:

// Method to Display Full Name
person.fullName = function() {
  return this.firstName + ' ' + this.lastName;
};

console.log(person.fullName()); // Output: John Doe

Object Constructor:

// Object Constructor Function
function Car(make, model, year) {
  this.make = make;
  this.model = model;
  this.year = year;
}

// Creating Instances of the Car Object
const car1 = new Car('Toyota', 'Camry', 2022);
const car2 = new Car('Honda', 'Accord', 2021);

Object Destructuring:

// Object Destructuring
const { firstName, lastName, age } = person;
console.log(firstName, lastName, age); // Output: John Doe 31

 

Summary

• Objects in JavaScript are used to store and organize data using key-value pairs.
• They can represent real-world entities, have properties and methods.
• Objects provide a way to structure and group related information for better code organization.
• Object properties can be accessed using dot notation or bracket notation.
• Object methods are functions stored within objects.
• Objects can be created using literal syntax, constructors, or destructuring.