I have to say i wasn't very impressed by it. The problem of "Typescript" or "Clojurescript" can't start with a line with "compiling into Javascript".

Because if that's the case, why do I need them, since Javascript isn't a difficult language at all.

Javascript does have its own issue but those issues are not perfectly solved by other language either. To be honest, Javascript can do as fast as any of these examples here, not to mention you can write a library to wrap it so that it can deliver these function even faster (with less lines). But making code hard to understand isn't the direction of any language.

Flexibility is a very strong sell-point of Javascript. By playing with `Haskell`, i did realize that some language do carry higher level advantage, but that requires higher level of thinking to take advantage.

In short, I think you can't beat a language by simply compiling into it. It's a loop.