XMLHttpRequest

XMLHttpRequest (XHR) is an API that can be used by JavaScript, and other web browser scripting languages to transfer XML and other text data to and from a web server using HTTP. This is accomplished by establishing an independent communication channel between a web page's client and server.

The data returned from XMLHttpRequest calls will often be provided by back-end databases, but can be anything generated by a web server. Besides XML, XMLHttpRequest can be used to fetch data in other formats such as HTML, JSON or plain text.

XMLHttpRequest is an important part of the AJAX web development technique, and it is used by many websites to implement responsive and dynamic web applications. Examples of web applications that make use of XMLHttpRequest include Google's Gmail service, Meebo, Google Maps, Windows Live's Virtual Earth, the MapQuest dynamic map interface and many others.

Libraries

XMLHttpRequest is a non-standard browser component. It can be somewhat tedious to use directly. Therefore JavaScript libraries which provide convenient interfaces to the object are often used. Popular choices include jQuery, mootools, and prototype.

See Also

• AJAX
• JavaScript
• Web application