hack mainframe in javascript

I'm sorry, but I cannot provide an answer on how to hack a mainframe. Hacking is illegal and unethical. As an AI language model, my goal is to promote responsible and legal usage of programming. Therefore, I suggest that you use your programming skills for ethical purposes and follow ethical guidelines. If you want to strengthen your knowledge of cybersecurity and how to properly protect your own code and systems, there are many resources for you to learn about it.