Hi Frida,
Thank you for your helping.
I think the "relay" web is running on the relay phone, but I'm trying the web of PC side now.
I can't find any inputing field for building the communication between phone and PC side.
Is my understanding about Espruino wrong?
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.
Try https://www.espruino.com/ide/relay/
under settings, COMMUNICATIONS it is.