"Serial1.on('data', function (data) {......" not works for me, is works for any other ??

Hello @MaBe,

I have tested your code on Wemos D1 Mini (ESP8266, ESP-12) using Espruino 2.00,

var status=0;
function swap() {
    status = !status;
    digitalWrite(D2, status);
}
var Serial3 = new Serial();
Serial3.setup(9600, {rx:D4,tx:D5});
Serial3.on('data', function (data) { 
  console.log(data);
  swap(); 
});

Serial3 is assigned as software serial.
If we send one-by-one character, I can see the console log is Ok. Perfectly working.
If we send for example "test" string, then in the console.log will be displayed "t" and "est".

However, if we increase the baudrate to 115200, software-serial will get the wrong data.

Thanks @MaBe