Where can I find regex to prevent code injection?

Recently, I discuss a lot about security, especially about code injection. And in these discussions, we talked a lot about regex are the only way to check if a string contains malicious code.

Curious as I am, I tried during hours to find some regex which can check if the string contains (one of them, not a big regex which can check all the cases) :

• SQL
• HTML
• Javascript

I only find for SQL, but it was on a random comment online, not even a post.

So, do you know where can I find these kind of regex?

Thanks a lot for your help!