Javascript Objects

In JavaScript, objects are a fundamental data structure used to store and organize related data and functionality. Objects are created using curly braces ({}) and consist of key-value pairs, where each key is a string (also known as a property name) and each value can be of any data type, including other objects.

JavaScript is an object-based language. Everything is an object in JavaScript.

• JavaScript is template-based not class-based. Here, we do not create the class to get the object. But, we directly create the objects.
• Objects in Javascript are basically data structures for storing and manipulating data. They help you structure your data and provide methods (or functions) for manipulating the data stored at any given time within your application. There are methods for creating them, adding properties, deleting properties etc.
• JavaScript provides several object methods that can be used to manipulate that data the way you want it.

A good example usage of objects:

Let's say we are creating a class attendance app. You can categorize your data and structure them in objects like so;

Accessing Object Properties

You can access object properties using dot notation or bracket notation.

myObjName.propertyName

or

myObjName["propertyName"]

Creating Objects in JavaScript

There are 3 ways to initialize an object.

Object literal Notation

The syntax for creating an object using object literal is given below:

let person = { name: "John",  age: 30,  city: "New York"};

As we can see above, property and value are separated by : (colon).

Let’s see by a simple example of creating an object in JavaScript.

Input:-

Output:-

By creating an instance of Object directly (using new keyword)

The syntax to create an object directly is given below:

Input:-

Output:-

Object Constructor

Now, we need to create a function with arguments or parameters. Each argument value can be assigned in the current object by using “this” keyword.

The this keyword will refer to the current object.

An example of creating an object using object constructor is given below.

Input:-

Output:-

Defining method in JavaScript Object

In JavaScript, you can define methods in objects by assigning a function to a property of an object. The property acts as the method name, and the assigned function becomes the method's implementation. Here's an example of defining a method in an object:

Input:-

Output:-

JavaScript Object Methods

The different methods for an Object are given below:

Do Not Declare Strings, Numbers, and Booleans as Objects!

When a JavaScript variable is defined with the keyword "new", the variable is created as an object:

var a = new String();        // Declares a as a String object

var b = new Number();        // Declares b as a Number object

var c = new Boolean();       // Declares c as a Boolean object

Note:- Avoid String, Number, and Boolean objects. They complicate your code and slow down execution speed.