返回函数的值

Question

我有这个功能：

const clientsIpAdress = (onNewIP) => {
  const MyPeerConnection =
    window.RTCPeerConnection ||
    window.mozRTCPeerConnection ||
    window.webkitRTCPeerConnection;
  const pc = new MyPeerConnection({
    iceServers: []
  });
  const noop = () => {};
  const localIPs = {};
  const ipRegex =
    /([0-9]{1,3}(\.[0-9]{1,3}){3}|[a-f0-9]{1,4}(:[a-f0-9]{1,4}){7})/g;

  const iterateIP = (ip) => {
    if (!localIPs[ip]) onNewIP(ip);
    localIPs[ip] = true;
  };
  pc.createDataChannel('');
  pc.createOffer().then((sdp) => {
    sdp.sdp.split('\n').forEach((line) => {
      if (line.indexOf('candidate') < 0) return;
      line.match(ipRegex).forEach(iterateIP);
    });

    pc.setLocalDescription(sdp, noop, noop);
  });
  pc.onicecandidate = (ice) => {
    if (!ice || !ice.candidate ||
      !ice.candidate.candidate ||
      !ice.candidate.candidate.match(ipRegex)) return;
    ice.candidate.candidate.match(ipRegex).forEach(iterateIP);
  };
};
export default clientsIpAdress;

当我写const时hey = clientsIpAdress（ip =＆gt; {return ip}） 它显示我未定义。为什么会这样？我可以使用回调吗？我有点困惑