Javascript complete tutorial for beginners

Object in Javascript

Learn Simpli May 15, 2021 no Comments

Object in Javascript

Introduction

JavaScript has an object entity with a combination of properties
An object has the key-value pair
Every element has a name which is called key
Objects help to group together different variable that belongs to the same person or entity
In object, the order doesn’t matter
The object in javascript can be created using the keyword Object
Every object in the javascript has properties associated with it
Properties of objects can be accessed with dot notation
You can only access the already assigned properties
If you try to access the properties those are not been assigned it will return undefined

//Create an employee object and assign properties:
//Employee object
var Employee = new Object();
Employee.name = 'Name';
Employee.designation = 'CEO';
Employee.email = 'name@gmail.com';
Access property of employee object:
var Employee = new Object();
Employee.name = 'Name';
Employee.designation = 'CEO';
Employee.email = 'name@gmail.com';
console.log(Employee.name);
//Output
//Name

Accessing property

You can only access the already assigned properties
If you try to access the properties those are not been assigned it will return undefined

var Employee = new Object();
Employee.name = 'Name';
Employee.designation = 'CEO';
Employee.email = 'name@gmail.com';
console.log(Employee.address);
//Output
//undefined

Key points

Object property name should be a valid string or
Object property name should be anything that can be converted to a string
Object property can not start with a number and if you want to use the number or string with space as property name then use the below format

var Employee = new Object();
Employee.name = 'Name';
Employee.designation = 'CEO';
Employee.email = 'name@gmail.com';
Employee['address of residence'] = 'The complete address';
console.log(Employee['address of residence']);
//Output
//The complete address

Ways create an object

With the help of object initializers: You can start creating an object by using the literal notation
With the help of the constructor function: You can create an object with the new keyword with the constructor
Using Object.create()

// With the help of object initializers
var Employee = {
    name: 'Name',
    email: 'name@gmail.com'
}
console.log(Employee.name);
//Output
//Name

//With the help of constructor function
// function Person(name, age, sex) {
    this.name = name;
    this.age = age;
    this.sex = sex;
}
var Person1 = new Person('Rajani', 33, 'M');
console.log(Person1.name);
// output
// Rajani

// Using Object.create()
// employee 1
var stark = Object.create(employee);
stark.name = 'Stark';
stark.tax = 200;
stark.salary = 20000;
var starkPayableSalary = stark.netPayable();
console.log(starkPayableSalary);

// employee 2
var mickel = Object.create(employee);
mickel.name = 'Mickel';
mickel.tax = 400;
mickel.salary = 30000;
var mickelPayableSalary = mickel.netPayable();
console.log(mickelPayableSalary);

// output
// Employee salary details:
// Name: Stark
// Tax : 200
// Payable amount is : 19800

// Employee salary details:
// Name: Mickel
// Tax : 400
// Payable amount is : 29600