A few days ago, I participated in, or more precisely, dropped by an online CTF contest held in Taiwan. Having no experience, most challenges were just nonsense to me. Except one, which was purely programmatic. This is an in-depth analysis of it. The challenge Author: Leko Challenge: Calculator 0x1 The description of this challenge was Javascript is the best programming language. That’s kind of a hint that suggests you to be prepared to exploit diverse JS syntactic tricks.