Read USB Serial data and write to SD card

I am new to Espruino and have just had a lot of difficulty with this. For that reason I am posting my solution for future reference. Sorry to raise the dead.

The following code allows me to toggle LED1 via echo 'a' > /dev/tty.usbmodem1411. I am not sure if the tty would be different for another user(?)

var state = false;
LED1.write(state);

Serial1.setup(9600);
Serial1.setConsole();
Serial1.on('data', function (data) {
  state = !state;
  LED1.write(state);
});