Object In JavaScript

A JavaScript object is an entity having state and behavior (properties and method). Example:mouse, car, pen, bike, chair, apple, keyboard, monitor etc.

Objects are variables too. But objects can contain many values.

Imp points:

The values are written as name:value pairs(name and value is separated by  a colon). The name:values pairs in JavaScript objects are called properties. 

var emp = {Name:"surya", address:"pune", age:20, salary:35000.56};

Property	Property Value
Name	surya
address	pune
age	20
salary	35000.56

JavaScript is template based not class based. So we don't create class to get the object. But, we direct create objects.

Creating Objects in JavaScript

There are 3 ways to create objects.

1.     By object literal

2.     By creating instance of Object directly (using new keyword)

3.     By using an object constructor

1) JavaScript Object by object literal

Syntax:

object={property1:value1,property2:value2.....propertyN:valueN}  

     Example:

<script> 

emp={name:"surya", address:"pune", age:20, salary:35000.56};

document.write(emp.name+" "+emp.address+" "+emp.age+" "+emp.salary); 

</script> 

Output :

surya pune 20 35000.56

2) By creating instance of Object

Syntax:

var objectname=new Object();  

where new is a  keyword which is used to create object.

Example:

<script> 

var emp=new Object(); 

emp.name="surya"; 

emp.address="pune"

emp.age=25;

emp.salary=35000.56; 

document.write(emp.name+" "+emp.address+" "+emp.age+" "+emp.salary);  

</script>

Output :

surya  pune  20  35000.56

3) By using an Object constructor

this keyword refers to the current object.

So you need to create function with arguments. Each argument value can be assigned in the current object by using this keyword.

Example:

  <script>  

   function stu(age,name,mark){  

   this.age=age;  

   this.name=name;  

   this.mark=mark;  

    } 

   ob1=   new stu (10,"surya",50);

   document.write(ob1.age+" "+ ob1.name+" "+ ob1.mark);  

  </script>  

   Output :

10 surya 50