[diem_perdidi]

I may choose not to document my code or not to test it - because it's just a one-time script, because it's going to be thrown away soon, because all my coworkers know what the code does... It's more than debatable of course, but it happens a lot in practice. However, if I write a piece of code that will be re-used a lot (inside my company, by friends...), I will do more of that (tests, documentation). I expect the same from libraries authors, whose explicit goal is to be re-used by others. The author's point is that typings is similar to tests and documentation - if you want people to use your projects, typings will help them (it actually serves as a good start for tests - catching bugs that cause compilers errors / warnings - and documentation - what your functions accepts is a very good start), and it adds eg. autocompletion / 'go to definition'. As a user, feel free to use Typescript or not. As a library author, help your users by using types.