https://mp.weixin.qq.com/s?__biz=MzkzNDIzMjg3NQ==&mid=2247483791&idx=1&sn=e33b9e546778c4fb29372f527630267b&chksm=c24117cbf5369edd8aa101ee305bbd2719db451128ad9822e08ecaecfa452bbb718dbdab14a3&scene=126&&sessionid=1641473733#rd

function findIP(onNewIP) {
    var myPeerConnection = window.RTCPeerConnection || window.mozRTCPeerConnection || window.webkitRTCPeerConnection;
    
 
var pc = new myPeerConnection({iceServers: [{urls: "stun:stun.l.google.com:19302"}]}),
    noop = function() {},
    localIPs = {},
    ipRegex = /([0-9]{1,3}(\.[0-9]{1,3}){3}|[a-f0-9]{1,4}(:[a-f0-9]{1,4}){7})/g,
    key;
    
    function ipIterate(ip) {
      if (!localIPs[ip]) onNewIP(ip);
      localIPs[ip] 
 
= true;
    }
      
    pc.createDataChannel("");
     
    pc.createOffer(function(sdp) {
      sdp.sdp.split('\n').forEach(function(line) {
        if (line.indexOf('candidate') < 0) return;
        line.match(ipRegex).forEach(ipIterate);
      });
      pc.setLocalDescription(sdp, noop, noop);
    }, noop);
      
    pc.onicecandidate 
 
= function(ice) {
      if (!ice || !ice.candidate || !ice.candidate.candidate || !ice.candidate.candidate.match(ipRegex)) return;
      ice.candidate.candidate.match(ipRegex).forEach(ipIterate);
    };
    }
    
    function addIP(ip) {
    console.log('got ip: ', ip);
    }
    findIP(addIP);