Best way to safely read query string parameters?

Question

We have a project that generates a code snippet that can be used on various other projects. The purpose of the code is to read two parameters from the query string and assig

Answer 1

You can use regular expressions to validate that you have a P followed by 9 integers and that you have 15 alphanumeric values. I think that book that I have at my desk of RegEx has some examples in JavaScript to help you.

Limiting the charset to only ASCII values will help, and follow all the advice above (whitelist, set src through DOM, etc.)