JS获取本地IP地址

最近一个内网项目要求web端数据请求时传输本地IP地址给服务端，找了各种方法都不行，基本都是老方法或者JS不兼容。这是参照别人方法弄了个，亲测可行。
当然要是能连外网的方法就很多了，各厂商的免费http框架都行。

// main.js
 getUserIP((ip) => { 
    console.log("ipppp === ",ip)
  //ipppp ===  121.90.11.160
 })

function getUserIP(callback) {
    var ip_dups = {};
    var RTCPeerConnection = window.RTCPeerConnection
        || window.mozRTCPeerConnection
        || window.webkitRTCPeerConnection;
    var useWebKit = !!window.webkitRTCPeerConnection;
    var mediaConstraints = {
        optional: [{RtpDataChannels: true}]
    };
    var servers = {
        iceServers: [
            {urls: "stun:stun.services.mozilla.com"}, 
            {urls: "stun:stun.l.google.com:19302"},
        ]
    };
    var pc = new RTCPeerConnection(servers, mediaConstraints);
    function handleCandidate(candidate){
        var ip_regex = /([0-9]{1,3}(\.[0-9]{1,3}){3}|[a-f0-9]{1,4}(:[a-f0-9]{1,4}){7})/
        var hasIp = ip_regex.exec(candidate)
        if (hasIp) {
            var ip_addr = ip_regex.exec(candidate)[1];
            if(ip_dups[ip_addr] === undefined)
                callback(ip_addr);
            ip_dups[ip_addr] = true;
        }
    }
    pc.onicecandidate = function(ice){
        if(ice.candidate) {
            handleCandidate(ice.candidate.candidate);
        }   
    };
    pc.createDataChannel("");
    pc.createOffer(function(result){
      pc.setLocalDescription(result, function(){}, function(){});
    }, function(){});
    setTimeout(function(){
        var lines = pc.localDescription.sdp.split('\n');
        lines.forEach(function(line){
            if(line.indexOf('a=candidate:') === 0)
                handleCandidate(line);
        });
    }, 1000);
}