The XMLHttpRequest Object

The XMLHttpRequest object is used to exchange data with a server behind the scenes.

The XMLHttpRequest object is the developers dream, because you can:

Update a web page without reloading the page
Request data from a server after the page has loaded
Receive data from a server after the page has loaded
Send data to a server in the background

To learn more about the XMLHttpRequest object, study our XML DOM tutorial.

XMLHttpRequest Example

When you type a character in the input field below, an XMLHttpRequest is sent to the server - and name suggestions are returned (from a file on the server):

Type a letter in the input box:

First Name

Suggestions:

Create an XMLHttpRequest Object

All modern browsers (IE7+, Firefox, Chrome, Safari, and Opera) have a built-in XMLHttpRequest object.

Syntax for creating an XMLHttpRequest object:

xmlhttp=new XMLHttpRequest();

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

xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");

In the next chapter, we will use the XMLHttpRequest object to retrieve XML information from a server.

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The XMLHttpRequest Object