Find out IP Address on the public side of a NAT using public stun server

GetIPAddress.js

function getIPAddress() {

    const S = "stun.l.google.com:19302";

    return new Promise(resolve=>{

        const pc = new RTCPeerConnection({
            "iceServers": [{
                "urls": ["stun:" + S]
            }]
        });

        const rslt = []
        pc.onicecandidate = e=>{

            if (!e.candidate) {
                return resolve(rslt);
            }

            if (e.candidate && e.candidate.candidate) {
                //https://tools.ietf.org/html/rfc5245#section-15.1
                const [ip,,, type] = e.candidate.candidate.split(" ", 8).slice(4);
                if(type == "srflx"){
                    rslt.push(ip);
                }
            }
        };

        pc.onnegotiationneeded = async()=>{
            await pc.setLocalDescription(await pc.createOffer())
        };

        pc.createDataChannel("");
    }
    );
}