public-ip.ts

async function getPublicIP(): Promise<string | null> {
  return new Promise((resolve) => {
    const pc = new RTCPeerConnection({ iceServers: [{ urls: "stun:stun.l.google.com:19302" }] });
    pc.createDataChannel("");

    pc.onicecandidate = (event: RTCPeerConnectionIceEvent) => {
      if (!event.candidate) return resolve(null);

      const parts = event.candidate.candidate.split(" ");
      const ip = parts[4];
      const type = parts[7];

      if (type === "srflx" || type === "relay") {
        resolve(ip);
      }
    };

    pc.createOffer()
      .then((offer: RTCSessionDescriptionInit) => pc.setLocalDescription(offer))
      .catch(() => resolve(null));
  });
}

// Usage
(async () => {
  const ip: string | null = await getPublicIP();
  console.log(ip); // e.g., "102.218.50.236" or null
})();