var wifi = require("Wifi"); wifi.scan((ap)=>print(ap));

I have the same problem with the same board shown above. It seem that the WiFi is not working properly on WeMos Dev board (weak WiFI, maybe?) with Espruino. Please try with other board. I try on an old NodeMcu board and it went ok. I said, 'weak WiFi' because running scan with MicroPython on the WeMos board returned only a few AP where there should be plenty. Give it a try on another dev board other then WeMos.