Learn Ajax
AJAX stands for Asynchronous JavaScript And XML. Ajax is not a programming language. It is a way to create better web standards. It was made popular by Google in 2005. When javascript was released, there was no means to transfer data between browser and server without refreshing the page. Ajax helps to solve this problem. Small bits of information can be retreived from the server without refreshing the page. The main purpose of Ajax is to provide a simple and standard means for a web page to communicate with the server without a complete page refresh.How AJAX works?
By using Ajax, the javascript communicates directly with the server by using JavaScript XMLHttpRequest object. In this way small bits of information can be excessed from the server without having to refresh the entire page. Hence, the entire page need not be loaded again and again making the application respond much faster. It improves the efficiency of the application.
An Example
Let's see an example of where Ajax is used. Consider a form to open an account on some emailing site like yahoo or gmail. It would be very frustrating to fill the complete form each time and click the submit button to check whether the username you provided is available or not. The page will refresh each time you click on the submit button. One easy way is to use Ajax. We can use an application to interact with the database constantly without having to reload the entire page each time. This is only one use of Ajax. Likewise, Ajax can be used in a variety of applications to increase their effciency.
A point to note:
Ajax is known as browser technology because it is dependent on the browser and is independent of web server software.
Ajax consists of the following:
- HTML and CSS for presenting.
- JavaScript (ECMAScript) for local processing, and DOM (Document Object Model) to access data inside the page or to access elements of XML file read on the server (with the getElementByTagName method for example)...
- The XMLHttpRequest class read or send data on the server asynchronously.