Ajax: The Definitive Guide

Chapter 12. Errors: To Be (in Style) or Not to Be

It amazes me how little coverage the topic of errors receives in programming and web development books today. I do not mean that authors gloss over the issue of errors—these books always address the mechanics of trying and catching errors. Rather, you do not see examples that illustrate what a developer should do with an error once it has been trapped. Coverage of error handling should comprise more than just how to alert the user that an error occurred. It should also comprise understanding what errors developers should allow the user to see and what errors they need to handle behind the scenes.

The basic question is where the error originated and why it occurred. Any error due to user-provided input should be sent back to the user. It’s harder to decide what to do with errors that were caused by the application.

Error Handling on the Web

When you think about JavaScript error handling on the Web, what immediately comes to mind? Many people think of a JavaScript alert box, or maybe a try-catch block within some JavaScript code. However, there is much more to error handling in a web application than just the errors that can occur within the JavaScript code. Web application developers must think about errors on the client side as well as on the server side.

Web application developers, especially those who utilize Ajax, cannot simply focus on what the client does, because the domain of the web developer stretches across client and server. ...