Adding JavaScript to a web application is a great way to add features that mimic those found in client/server applications without sacrificing all the benefits of web deployment. Oracle Application Express includes multiple built-in interfaces especially designed for adding JavaScript.
Remember that JavaScript is not appropriate for data intensive validations. For example, to verify that a name is contained within a large database table, you must pull down every record to the client, creating a huge HTML document. In general, complex operations are much better suited for server-side Application Express validations instead of JavaScript. To learn more, see the JavaScript discussion for the appropriate control or component.
See Also:
"Text with JavaScript Escaped Single Quotes" for information about referencing a shortcut inside of a JavaScript literal string, "Understanding Validations," and "About Using JavaScript Code in a Plug-In"