It's been ages since my last dive into the js galaxy, but from my outside perspective I read that as "the usual mess that we like to do to provide awesome backw

It's been ages since my last dive into the js galaxy, but from my outside perspective I read that as "the usual mess that we like to do to provide awesome backwards compatibility when introducing wildly changed API generations is very difficult to sneak past the typechecker". Not sure that I read it correctly, but it would certainly fit "conditional types, type operators, and overloads". Why are they more prevalent in library code: to make changes non-breaking (or breaking, but fixable with minor tweaks). Of course types can also be a solution to this problem, by promoting consequences of incompatible change from runtime to compile time, but that only holds if you can assume that all calling code is type checked.