Book Image

AJAX and PHP: Building Responsive Web Applications

Book Image

AJAX and PHP: Building Responsive Web Applications

Overview of this book

Assuming a basic knowledge of PHP, XML, JavaScript and MySQL, this book will help you understand how the heart of AJAX beats and how the constituent technologies work together. After teaching the foundations, the book will walk you through numerous real-world case studies covering tasks you'll be likely to need for your own applications: Server-enabled form-validation page Online chat collaboration tool Customized type-ahead text entry solution Real-time charting using SVG Database-enabled, editable and customizable data grid RSS aggregator application A server-managed sortable list with drag&drop support using the script.aculo.us JavaScript toolkit The appendices guide you through installing your working environment, using powerful tools that enable debugging, improving, and profiling your code, working with XSLT and XPath. From the Author, Cristian Darie AJAX and PHP: Building Responsive Web Applications is mainly a book for beginners, but when designing its contents we tried to find the ideal blend of topics that would help both novice and experienced web developers make a big step forward. One customer was very kind to let us know, through a review, that we succeeded: "The theory behind all the technologies used is very clearly explained, without boring you with details about obvious things. Right from the first chapter you start learning by examples. The examples can be easily adapted to many web projects and they cover stuff that is both useful and fun." Here are a few examples of such "useful and fun" things that you can find in this book: details on using proxy scripts to work around the security measures in modern browsers client-side and server-side code that doesn't break when fed with special characters (such as <, ", etc) code that works efficiently with Internet Explorer 5, 6 and 7, Firefox, Opera, Safari, and others a very quick introduction to SVG, the new rebel kid of the web (and of the house) client-server communication based on message queues that guarantee that your messages aren't lost on the way, and arrive in the intended order at the destination server-side state management techniques that use query string parameters and database records to keep track of your client's activity simple yet effective error-handling structures that combine JavaScript code and PHP code to report when something bad happens on the client or on the server a live errata page that is updated as soon as anyone reports a suggestion or a correction a friendly AJAX tutorial and many case studies that teach you how to use JavaScript, PHP, MySQL and XML together in order to achieve wonderful results The book's authors and the publisher are listening to your feedback, and appreciate when you invest some time to let them know what you think. The first result of this collaboration is an updated version of the AJAX Chat case study that uses (and teaches) JSON instead of XML. Find this new chapter in the code download or on my website. Thanks for reading such a long message. Have fun!" Cristian Darie.
Table of Contents (17 chapters)
AJAX and PHP
Credits
About the Authors
About the Reviewers
Preface
Index

Chapter 4. AJAX Form Validation

Validating input data is an essential requirement for quality and secure software applications. In the case of web applications, validation is an even more sensitive area, because your application is widely reachable by many users with varying skill sets and intentions.

Validation is not something to play with, because invalid data has the potential to harm the application’s functionality, and even corrupt the application’s most sensitive area: the database.

Input data validation means checking whether the data entered by the user complies with previously defined rules, which are established according to the business rules of your application. For example, if you require dates to be entered in the YYYY-MM-DD format, then a date of “February 28” would be considered invalid. Email addresses and phone numbers are other examples of data that should be checked against valid formats.

Note

Carefully define the input data validation rules in the software requirements...