Create Object

An object of XMLHttpRequest is used for asynchronous communication between client and server.
All modern browsers support the XMLHttpRequest object (Except IE5 and IE6 use an ActiveXObject).
The XMLHttpRequest object is used to exchange data with a server behind the scenes. This means that it is possible to update parts of a web page, without reloading the whole page.

Create an XMLHttpRequest Object

We can create an instance of the XMLHttpRequest of all popular browsers(Firefox, Chrome, IE7+, Safari, and Opera)
All modern browsers (IE7+, Firefox, Chrome, Safari, and Opera) have a built-in XMLHttpRequest object.

Syntax

 
var variable_name;
variable_name=new XMLHttpRequest();

var variable_name=new XMLHttpRequest();

Create an object of ActiveXObject for old browsers(IE5 or IE6)

Old versions of Internet Explorer (IE5 and IE6) uses an ActiveX Object:

Syntax

 
var variable_name;
variable_name=new ActiveXObject("Microsoft.XMLHTTP");

var variable_name=new ActiveXObject("Microsoft.XMLHTTP");
Note: To handle all modern browsers, including IE5 and IE6, check if the browser supports the XMLHttpRequest object. If it does, create an XMLHttpRequest object, if not, create an ActiveXObject.