Ajax Programming for the Absolute Beginner

introduction

welcome to Ajax Programming for the Absolute Beginner! Ajax (Asynchronous
JavaScript and XML) is a collection of web development technologies that
can be used to create web applications that provide levels of responsiveness
previously unheard of. As a result, when combined with high-speed internet connections,
you can use Ajax to develop web applications that behave and respond
like desktop applications.
In recent years, web developers have begun to make major investments in Ajax,
using it to create a whole new generation of web applications. For example, Google
has used Ajax in the creation of all its latest applications, including Google Suggest,
Google Maps, and Gmail. Amazon.com has used Ajax in the development of
its A9.com search engine as well as to enhance and improve its main website.
Websites like Ask.com and Snap.com have used Ajax to make major improvements
to their search engines. Other companies have used Ajax to help develop entire
office suites of free online applications. For example, ThinkFree Online
(www.thinkfree.com) can create text documents, spreadsheets, and presentations
all of which are 100 percent compatible with Microsoft Office. Google’s Google
Docs Online office suite (docs.google.com) is another example of online applications
developed using Ajax.

When it comes to web development, Ajax is truly the “next big thing.” Ajax is
becoming an essential ingredient in the makeup of modern web applications. Ajax
is being used in the development of all kinds of exciting new applications and
rightly so, given its ability to support the creation of web applications with
desktop-like performance.
Using Ajax programming techniques you can transform the way your web applications
look and feel, providing your visitors with a significantly enriched experience.
By learning how to create Ajax applications, you will develop a highly
marketable set of skills that are currently in high demand. To help you accomplish
this goal, this book uses a hands-on instructional approach, emphasizing learning
by doing, which is accomplished through the development of a series of computer
games.
So, whether you are a student who has just signed up for an introductory web development
class that uses Ajax, a hobbyist who wants to have some fun, or a web developer interested
in expanding your skill set, this book will help you get off to a good start. By the time you are
done, you will be ready to begin taking your web applications to the next level


WHY AJAX?
Ajax changes the way in which web applications are designed, replacing requests for new web
pages and screen refreshes with small data queries to web servers. By requesting less data,
the web servers are able to respond quicker. Ajax data requests are made asynchronously,
meaning that users no longer have to sit and wait for the web server to fulfill a request.
Instead, the user can continue to work with the web application while Ajax collects and processes
the web server’s data in the background, and when it is time to do so, Ajax can use the
data to dynamically update the web page without forcing a page reload. The end result is a
streamlined, faster, and more desktop-like experience.
Because it relies on commonly available technologies like JavaScript and XML, Ajax is readily
available and supported by all major computer operating systems and web browsers. You do
not have to download and install any special software to work with Ajax, and the people who
visit your website do not have to install anything to view and interact with your Ajax
applications


WHO SHOULD READ THIS BOOK?
Ajax Programming for the Absolute Beginner is designed to teach first-time programmers, computer
enthusiasts, and web developers interested in adding Ajax to their bag of tricks. An
understanding of HTML is required for you to complete this book. While previous programming
experience is certainly helpful, as is a basic understanding of JavaScript, the DOM, CSS,
the XMLHttpRequest object, and XML, you do not need to be an expert with any of these technologies.
You will learn all that you need to know about each of these technologies as you
make your way through this book.
In addition to teaching you everything you need to know to get up and running quickly, this
book will make your learning experience as enjoyable as possible. This will be accomplished
using a games-based instructional approach in which you will learn Ajax programming
through the creation of web-based computer games. If this approach to learning sounds interesting
and fun to you, then keep reading. It won’t be long before you are creating all kinds
of fun and exciting web applications


WHAT YOU NEED TO BEGIN?
Ajax is not something that you can buy in a box or download from the internet. It is a collection
of related technologies that are readily available to everyone. Because it is based on
technologies like JavaScript, XML, and the DOM, it is readily available. You do, however, need
a few tools and resources to get started. Ajax uses JavaScript as its programming language. In
order to develop JavaScript code, you need a text or code editor. If you already have a code
editor that you are using to develop your HTML pages, odds are it will support JavaScript as
well. Otherwise, you can use any plain text editor, such as Windows Notepad, when developing
Ajax applications.
In addition to an editor, you will need access to one or more web browsers like Internet
Explorer, Safari, Firefox, or Opera to test your web applications. Because Ajax applications
are designed to work with web servers, you also need access to a web server and the ability to
develop programs that run on the server. For most people this means signing up with one of
the many available web service providers.
Most Ajax applications involve the development of some server-side programs. In this book,
server-side applications (programs that run on web servers) are developed using PHP. Although
the use of PHP will be minimal, to follow along with and test the execution of all of
the examples in this book, you will want to make sure that your service provider supports the
execution of PHP.


Working with Different Web Browsers
Ajax uses JavaScript as its programming language. As such, Ajax is susceptible to all of the
same problems that JavaScript programmers face. One of these compatibility issues involves
the browser. Due to internal design differences, different web browsers work differently with
JavaScript and therefore with Ajax. To properly test your Ajax applications, you should use
all major web browsers, including those listed below, to make sure that they behave as you
expect them to.
• Internet Explorer
• Apple’s Safari
• Mozilla Firefox
• Opera
Most of the figures and examples that you will see in this book are demonstrated using Internet
Explorer 7. Except where noted, all of the examples that are presented in this book
should work exactly the same on all of the major web browsers.


What You Need to Know
In order to take advantage of this book, you need to be familiar with the basics of HTML
development and, of course, you need a website that you can work with and are interested
in making more responsive and dynamic. Beyond that, this book will provide everything else
you need to know. This includes an overview of how to program using JavaScript and the
Document Object Model. This book also provides a basic review of XML and CSS.
Ajax applications have a server-side component needed to make them work. There are many
different server-side programming languages from which to choose, including Ruby on Rails,
PHP, Java Servlets, and ASP. Of these, PHP is arguably the most popular and easiest to work
with and is the server-side programming language that this book uses. You will not have to
become a PHP guru in order to make your way through this book. However, a basic understanding
of PHP will be helpful. To make sure you have a basic understanding of PHP
programming, this book provides a quick server-side PHP programming primer.
to download this course click here