ESP8266 - Uncaught Error: Field or method does not already exist, and can't create it on undefined

@Gordon thanks for your response.

I have tried only this code, but result is the same:

Serial4.setup(115200, { rx: C11, tx : C10 }); 
var wifi = require("ESP8266").connect(Serial4, function() {   
wifi.connect("WiFi_Name","WPA2_Key", function() {   
}); 
});

I think you are pointing this thread on the forum : http://forum.espruino.com/conversations/253943/?offset=25
I'm going to check it.

Thanks.