Well, sometimes, which is why optional type signatures, like those in TS, can be useful. But even if you're not telling all the typing details, at least tell th

Well, sometimes, which is why optional type signatures, like those in TS, can be useful. But even if you're not telling all the typing details, at least tell the world that your function works with strings, or whatever. And if you're using the properties everywhere, yeah, define them, but if you need to extend an object, and the extension will only be used locally, than it's useful.