The unhandled or unexpected script error is a real issue these days. Script errors can be seen even on many of the professionally designed Web sites and Web-based customer applications. Sometimes the errors are shown only on specific browser versions; sometimes date/time-related issues cause them, while in some other cases programming errors do. And most of the time the error message the Web browser shows does not make any sense to the common users.
The right way to tackle an unexpected error that may occur on a Web page is through the onError event. This onError handler method should appear as the first line of the script code. In fact, it’s a good idea to put an onError handler function on every page that has got scripts on it.
If you don’t have specific error handling in this function, you could at least show the user a friendly message rather than the browser-specific messages that appear. And if you do not want to have any error handling at all, just put the following code on top of every page that contain scripts:
Alternatively, you could use a default error handler that is more like a placeholder for future enhancements on error handling, as follows.
Returning true from the error handler tells the browser to suppress all error messages. You can show the users your own messages before returning true. Or if you prefer to handle the error and then show the browser’s warning/error messages, return false from this function. As mentioned earlier, the third option is setting the error handler to null, which doesn’t take care of any handling or show the user any message.