Object

In JavaScript object is a real-world entity having properties like states and behavior.
An object is used to store and organize data using a key-value pair structure.

Creating an object in JavaScript:

There are 3 ways to create an object in JavaScript:

Using object literal notation
Using a new keyword(by creating an instance of an object directly)
Using Object Constructor (new keyword).

Using Object literal notation

The simplest way to create an object is by using object literal notation.
object's properties and values are defined inside curly braces {}.

Syntax:

var person = {
    firstName: "John",
    lastName: "Doe",
    age: 30
};

Example:

<html>

<body>
  <script>
    emp = { id: 102, name: "Shyam Kumar", salary: 40000 }
    document.write(emp.id + " " + emp.name + " " + emp.salary); 
  </script>
</body>

</html>

Output:

102 Shyam Kumar 40000

Using a new keyword(by creating an instance of an object directly)

Syntax:

var objectname=new Object();

Example:

<html>

<body>
  <script>
    var emp = new Object();
    emp.id = 101;
    emp.name = "Ravi Malik";
    emp.salary = 50000;
    document.write(emp.id + " " + emp.name + " " + emp.salary); 
  </script>
</body>

</html>

Output:

101 Ravi Malik 50000

Using Object Constructor (new keyword)

You can create an object using the object constructor.

Syntax:

var person = new Object();
person.firstName = "John";
person.lastName = "Doe";

Example:

<html>

<body>
  <script>
    function emp(id, name, salary) {
      this.id = id;
      this.name = name;
      this.salary = salary;
    }
    e = new emp(103, "Vimal Jaiswal", 30000);
    document.write(e.id + " " + e.name + " " + e.salary); 
  </script>
</body>

</html>

Output:

103 Vimal Jaiswal 30000