A browser is a script that has some manual bits to it. You should never assume that requests to your site are coming in any order, based on any information you gave in the last response, or, frankly, with any structure. Not only will this make your application capable of handling scripts, but it will also make your application more secure.
The first thing a cracker tries to do is find out what your application responds to by reading your HTML. Then, they try different variations of the parameters. Sound familiar?
My criteria for good software:
- Does it work?
- Can someone else come in, make a change, and be reasonably certain no bugs were introduced?