Just to add - the ESP8266 isn't exactly wrong in this case - it's just that I imagine the upload takes longer over serial, and things won't be scheduled quite as well because you're reliant on the underlying RTOS.
Espruino is a JavaScript interpreter for low-power Microcontrollers. This site is both a support community for Espruino and a place to share what you are working on.
Just to add - the ESP8266 isn't exactly wrong in this case - it's just that I imagine the upload takes longer over serial, and things won't be scheduled quite as well because you're reliant on the underlying RTOS.