What is Object in JavaScript?

In JavaScript, objects are king. If you understand objects, you understand JavaScript.

In JavaScript, almost "everything" is an object.

• Booleans can be objects (if defined with the new keyword)

• Numbers can be objects (if defined with the new keyword)

• Strings can be objects (if defined with the new keyword)

• Dates are always objects

• Maths are always objects

• Regular expressions are always objects

• Arrays are always objects

• Functions are always objects

• Objects are always objects

All JavaScript values, except primitives, are objects

Syntax

const person = {
        firstName:"John",
        lastName:"Doe", 
        age:50, 
        eyeColor:"blue"
};

JavaScript Object Methods

JavaScript methods are actions that can be performed on objects.

A JavaScript method is a property containing a function definition.

Accessing Object Methods

You access an object method with the following syntax:

objectName.methodName()

Example :

name = person.fullName();

Adding a Method to an Object

person.name = function () {
  return this.firstName + " " + this.lastName;
};

Using Built-In Methods

This example uses the toUpperCase() method of the String object, to convert a text to uppercase:

let message = "Hello world!";
let x = message.toUpperCase();
//Output :  HELLO WORLD!

Resources :

w3school