Javascript HTML5视频的GetUserMedia在chrome中没有选择面向用户的摄像头

因此，我的任务是使用HTML5视频元素创建一个演示，以获得用户的图片，然后在服务器端进行一些处理。在Surface Pro 4上测试似乎忽略了navigator.mediaDevices.getUserMedia函数中的facingMode:“用户”选项

    navigator.mediaDevices.getUserMedia({ audio: false, video: { facingMode: "user" } })
    .then(handleSuccess, stopCameras);

    var handleSuccess = (stream) => {
        customer.srcObject = stream;
        videotracks = stream.getVideoTracks();
    }

handleSuccess调用流上的getVideoTracks，但阵列中只有后向摄像头

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如何确保这只针对面向用户的摄像头？

您需要首先枚举摄像头的数量，并将其保存在一个变量中，如下所示：

var camcounter; // camera counter
var camera_id = {}; // array of cameras by device id

navigator.mediaDevices.enumerateDevices()
.then(function(myStream) {
    myStream.forEach(function(myStream) {
        if(myStream.kind === 'videoinput') {
            camcounter++; //camera count
            camera_id.push(myStream.deviceId); //pushing the device ID to the array
            console.log(myStream.kind + ": " + myStream.label + " id = " + myStream.deviceId);                        
        }
    });
})
.then(function(myStream) { 
    if(camcounter === 1) { //building mediaContraints if just one camera found
        console.log('one camera profile');
        mediaConstraints = {
            video: {deviceId: {exact: camera_id[0]}},
            audio: {mandatory: {echoCancellation: true, googAutoGainControl: true, googNoiseSuppression: true, googHighpassFilter: true, googTypingNoiseDetection: true}}
        };
    }
    else {
        if(camcounter === 2) { //building mediaContraints if two cameras found
            mediaConstraints = {
                video: {deviceId: {exact: camera_id[1]}},
                audio: {mandatory: {echoCancellation: true, googAutoGainControl: true, googNoiseSuppression: true, googHighpassFilter: true, googTypingNoiseDetection: true}}
            };
        }
        else {
            console.log('no camera or more than 2 cameras');
        }
    }
})
.then(function(myStream) {
    navigator.mediaDevices.getUserMedia(mediaConstraints)
        .then(function(myStream) {
            stream = myStream;
            usercam1.srcObject = stream;       
            pc = new PeerConnection(servers);      
            pc.addStream(stream);
            pc.ontrack = function(e) {
            usercam2.srcObject = e.streams[0]; 
        };
        pc.onicecandidate = function(event) {
            if(event.candidate) {
                send({type: 'candidate', candidate: event.candidate});   
            }
        }; 
    })
})
.catch(function(error) {
    console.log('error switching camera :' + error + ' camecounter is: ' + camcounter);
 });

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可能的副本必须对此进行检查并报告！