What is AJAX ?

AJAX is “Asynchronous Java Script and XML”. AJAX is a type of programming, which became popular in 2005 by Google,  Mainly used to refresh a part of a HTML/JSP  page but not the entire page.

With AJAX we can create better, faster, and more user-friendly web applications.

AJAX is based on Javascript and HTTP request .Data retrieval is commonly in the form of XML and using DOM we will parse the XML and populate the data we need.

One example for applying AJAX is Alphabet and name .In this example , We have all the alphabets in the drop down list and on select of any alphabet , the list of all the names starting with that particular alphabet will be showing in a list box.In this situation we can use  “AJAX” to send the request to back end for getting the Names list.As we are sending the request in back end and we are not waiting for the response, we can continue with another operations on the page.Using Java Script, onChange event of the alphabet  we will send the request using the XMLHTTPRequest object to a back end process to handle the request and then the response we will get as an XML, using DOM we will parse the XML and populate the data and display the names.