I’m not a regular JS user and haven’t touched the language in a long time, but I remember a (popular?) website for teaching modern JavaScript mentioned that some aspect of the function/macro that returns the type of an object was just plain wrong in a specific and important case. This was years ago however, so maybe the problem isn’t there anymore. Anyhow, I added JS to the list mainly because it is known as a badly designed language and Brendan Eich seems to agree.