By using defensive scripting techniques, including object detection, you can ensure that your scripts don't crash or generate errors. Add error-handling mechanisms to create bulletproof scripts. When implementing these techniques, you are likely to receive less feedback from your users, because they won't need to report your annoying JavaScript errors. In this column you learned:

1. How to determine which browser the user is running.
2. How to find out if a specific object exists.
3. How to find out if a specific method exists.
4. How to ignore errors when they occur.
5. How to cut & paste common object detection routines.