Your first AJAX application

Your first AJAX application
To understand how AJAX works, we will create a small AJAX application.
First we are going to create a standard HTML form with two input fields: Name and Time. The "Name" field will be filled out by the user, and the "Time" field will be filled out with AJAX.
The HTML file will be named "testAjax.htm", and it looks like this (notice that the HTML form below has no submit button!):


The next chapters will explain the keystones of AJAX.

AJAX uses the XMLHttpRequest object

To get or send information from/to a database or a file on the server with traditional JavaScript, you will have to make an HTML form, and a user will have to click the "Submit" button to send/get the information, wait for the server to respond, then a new page will load with the results. Because the server returns a new page each time the user submits input, traditional web applications can run slowly and tend to be less user-friendly.

With AJAX, your JavaScript communicates directly with the server, through the JavaScript XMLHttpRequest object With the XMLHttpRequest object, a web page can make a request to, and get a response from a web server - without reloading the page. The user will stay on the same page, and he or she will not notice that scripts request pages, or send data to a server in the background.

The XMLHttpRequest object

By using the XMLHttpRequest object, a web developer can update a page with data from the server after the page has loaded!
AJAX was made popular in 2005 by Google (with Google Suggest).
Google Suggest is using the XMLHttpRequest object to create a very dynamic web interface: When you start typing in Google's search box, a JavaScript sends the letters off to a server and the server returns a list of suggestions.
The XMLHttpRequest object is supported in all major browsers (Internet Explorer, Firefox, Chrome, Opera, and Safari).

AJAX is based on Internet standards

AJAX is based on the following web standards:
JavaScript
XML
HTML
CSS

AJAX is about better Internet-applications
Internet-applications have many benefits over desktop applications; they can reach a larger audience, they are easier to install and support, and easier to develop.
However, Internet-applications are not always as "rich" and user-friendly as traditional desktop applications.
With AJAX, Internet applications can be made richer and more user-friendly.

There is nothing new to learn.
AJAX is based on existing standards. These standards have been used by developers for several years.