In this tutorial we will learn about the properties of an object in JavaScript, classification of the properties, attributes of properties.There are 3 kinds of properties an object in JavaScript have:

1: Data Property: In this property of javascript object the data is represented by the key: value pairs.

For Example: object abc has a data property whose name is the string "prop1" and whose value is the number 456.

    var abc = {
        prop1: 456
    };

This property has following attributes

value : (It's the properties value) writable : (It can be set as true or false) enumerable : (It can be set as true or false, so that the property show in a loop constructs) configurable : (It can be set as true or false, so that the property can be deleted)

2: Accessor Property: This property is of 2 types

2.1- getter property: Using the getter property we can dynamically change the values by calling the function implicitly.This property has the following attributes.

a. enumerable
b. configurable
c. get

2.2- setter property: Using the setter property we pass a value as an argument and the setter function returns a value.The call made here is also implicitly.This property has the following attributes.

a. enumerable
b. configurable
c. set

Note: writable and value Attribute does not exist for getter and setter properties.

Example of getter & setter property:

<script>
        var obj = {

       get_prop() {
            document.write("get_prop function is called implicitly");
        },

       set_prop(value) {
            document.write("set_prop function is called implicitly and passes a value as an argument: "+value);
        }
    }

    obj.get_prop();     
    obj.set_prop(562);

    </script>

Output for get_prop: get_prop function is called implicitly
Output for set_prop: set_prop function is called implicitly and passes a value as an argument: 562

3: Internal Property: These properties are represented by double square brackets

For Example: one of the internal properties is [[Extensible]]

[[Extensible]] : This internal property determines can we add more properties to an object or not. We can read it using Object.isExtensible() and set it false using Object.preventExtensions().