[fedlarm]

I used to share this opinion as well, until I started working on an internal library that was created by a skilled developer. He had very good test coverage and good quality tests, which turned out invaluable, once I got on board. We tried to move to library towards being fully typed in TypeScript, just to get some experience with TypeScript. Our first thought before starting was, that it would help, but didn't expect it to have a significant impact. During the port to TypeScript (and being strict on typing everything possible), we soon found numerous unexpected behaviors in the code. Some of the issues found, could have been found by a linter, but other things like models changing over time was only found due to adding static types.

After this experience I changed my opinion towards the value of static types, from being more than a nice to have feature.