While I definitely appreciate types and normally work with the languages like C++ sometimes I do some front end JS libs and frankly do not have any mental troubles using plain JS. As for whether it is "safe" - all that matters to me if it works to specs and the customers are happy. Since I am programming since like forever I guess I've got enough discipline, common sense, knowledge and experience to produce decent code.

I've never had issues doing huge refactors in JS. But thanks for telling me I'm just wrong.

for me I make sure to write thorough unit tests along with clear, concise code

To each their own though. I wrote code without any kind of autocomplete or tooling for a very long time because I felt like it. Sometimes when you don’t have something helping you all the time, it keeps you sharper.