It doesn't try to protect you from the really deranged things. Every TS check comes with an implied "assuming you didn't use a Proxy to make this property acces

It doesn't try to protect you from the really deranged things. Every TS check comes with an implied "assuming you didn't use a Proxy to make this property accessor mutate state or something" It does reach admirably far into checking the regular dynamic-language programming patterns like using string variables to index into structures. Which is where a lot of its complexity comes from, but I wouldn't call that stuff "deranged". JS is a dynamic programming language, and people write it like a dynamic programming language, and typescript decided to meet it where it was at, which is probably the only reason it's gotten so much traction in the first place