AJAX - XMLHttpRequest object

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

XMLHttpRequest object

All modern browsers (Chrome, Firefox, IE7 +Edge, Safari, Opera) all have built-in XMLHttpRequest objects.

XMLHttpRequest allows asynchronous updates of the web page by exchanging data with the background web server.

You can retrieve data from a URL without refreshing the entire page.

This allows the web page to update a part of the page without interrupting the user's operation.

Create an XMLHttpRequest object

Before executing AJAX communication between the client and the server, the first thing to do is to instantiate an XMLHttpRequest object, as shown below:

Syntax:

var request = new XMLHttpRequest();

var httpRequest = new XMLHttpRequest();

Cross-site XMLHttpRequest

For security reasons, modern browsers do not allow cross-domain access.

This means that both the web page and the requested files it tries to load must be on the same server.

w3Examples on codebox.com are all opened in the w3All open request files in the codebox.com domain.

If you want to use the above example on one of your own web pages, the requested file must be located on your own server.

Older browsers (suitable for IE 6and earlier versions)

Old versions of Internet Explorer (6and earlier versions) use ActiveX objects instead of XMLHttpRequest objects.

Syntax:

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

To handle IE6and earlier versions, please check if the browser supports the XMLHttpRequest object, otherwise create an ActiveX object:

var httpRequest;
if (window.XMLHttpRequest) {
　　　　//　The mainstream browsers (Chrome, Mozilla, Safari, IE7+, ...)
　　　　httpRequest = new XMLHttpRequest();
else if (window.ActiveXObject) {
　　　　//　<=　IE　6　or earlier IE versions
　　　　httpRequest　=　new　ActiveXObject("Microsoft.XMLHTTP");
}

XMLHttpRequest Object Properties

The following table lists all properties of the XMLHttpRequest object:

XMLHttpRequest Object Methods

The following table lists all methods of the XMLHttpRequest object: