Javascript is dynamically typed -- that does not mean it has no types. You are free to add dynamic type checks anywhere you want. I view these as critical for A

Javascript is dynamically typed -- that does not mean it has no types. You are free to add dynamic type checks anywhere you want. I view these as critical for APIs even if you decide to use typescript. I also view them as critical for third-party interfaces where you may not be able to test integrations completely.