Which is the most used programming language for Arduino ?

Question

Arduino Programming

Answer 1

You can use c++, c and AVR assembler code to program the Microcontroller(MCU).
If you develop a communication protocol for your MCU, you can use any pogram to leverage that protocol from an external device.
A common example for this is loading the firmata firmware and have some external programs communicating via serial port using the firmata protocol.
Don't expect to program the MCU directly in JavaScript, Java nor Python.

Answer 2

The most used language are c++ or javascript