Is it possible to program Arduino in transpiled JavaScript? Coming from JS, I find it very difficult to program Arduino in C++ (not even knowing which version or what features are supported), being bound to the loop and delay, not being able to (easily) use anonymous functions in parameters or async code.

I know JS isn't natively supported by Arduino, but I know languages can be transpiled.

I have seen many solutions, so just to pick few:
JohnnyFive J5, which runs via cable on a host PC,
NectarJS with their arduino-uno target,
or andrei-markeev/ts2c which converts ES3 to C89.

Each of them come with their own limitations and it's very difficult to find the right without prior experience with IoT. Did anyone walk this path already and found a viable solution?
Even if such a transpiler exists (which I don‘t know) you will still have to deal with the loop structure and the fact that you should avoid using delays. On a microcontroller you have to forget about things like multithreading and even dynamic memory allocation should be used carefully.
Most of those things that make a programmer‘s life easy on bigger systems are usually paid with ram or cpu power, but on a microcontroller with some kB RAM there are only few resources to pay with.

So my recommendation is to learn C++ instead of looking for ways to convert code from another language, which will probably introduce its own problems. You‘ll soon find yourself one layer below and there are exciting things that higher languages hide from you.