What is Ajax?

Introduction to Ajax

Ajax stands for Asynchronous JavaScript and XML . Ajax is a client-side scripting language .

From the name , we can conclude that it is  javascript dependent i.e. Ajax is browser dependent .

Ajax is the most popular and Rich Internet Application (RIA) technology now a days .We can say that in Every project from Web to Mobile Ajax is widely used by developers.Ajax is introduced by Google (in Google Search suggestion) in the year of 2005 .

 

Why we use Ajax?

In most of the scenario we need  to fetch data from server and require  to show on the  current page or some portion of the web page without pageloading and refreshing of entire page . for example , like in Gmail, during email  id creation system checks automatically whether any user exists with desired username or not .So, we can define ajax as

“Ajax client side scripting language which provides an easy way to retrieve data from a URL i.e, from server without having to do postback (reload)  or  refresh of  entire webpage.”

In Short, we can say that, we can say that a request automatic or on click etc. goes to server through ajax request in background(i.e., the user would never know that any request was even gone to the server) and the server returns some result which will be display in the some portion of the webpage without reloading or refreshing the entire webpage. 

Scenario where we can use Ajax –

Suppose we have Registration page, during registration we need to check whether given email id already exist or not on email’s textbox change without any page load or page refresh. if exist then message appears like above .

In this scenario, we are going to call an Ajax request on email’s textbox change to check the above. For doing this, we need to create a database driven Java servlet / jsp page which checks that the email id exist in database or not .