That's intended -
digitalReadautomatically sets the pin state to input when you use it (in the same way you'd be surprised if
digitalWritedidn't change the pin state to an output).
You can manually set the pin mode with
pinModethough, and then it won't change state after that so you can do a
digitalReadwhile leaving the LED on.
Whilst working on an addition ontop of UART.js ive found that digitalRead(LED) will turn off LED is this a bug or intended?