All JS APIs are typed (browser, nodejs, etc.), if you meant libraries, yes, not all of them are typed. But the vast majority have community types in DefinitelyT

All JS APIs are typed (browser, nodejs, etc.), if you meant libraries, yes, not all of them are typed. But the vast majority have community types in DefinitelyTyped. Also, it is trivial to type an unknown library yourself, or at least type only the relevant parts for your work.