Change camera failed in Chrome

[xxxxxxbin6]

I try to change camera in chrome,but failed.Can someone help me figure out the problem?It's my code:

var peers

webrtc.connection.on('message', (message) => {
peers = webrtc.getPeers(message.from, message.roomType)
})

$('.switch-camera img').on('click', () => {
const mediaStreamContrains = {
video: {
deviceId: {
exact: window.selectedCamera,
},
},
}
navigator.mediaDevices
.getUserMedia(mediaStreamContrains)
.then((stream) => {
var videoTrack = stream.getVideoTracks()[0]
var sender = peers[0].pc.pc.getSenders().find(function (s) {
return s.track.kind == videoTrack.kind
})
console.log('sender', sender)
sender.replaceTrack(videoTrack)
})
.catch((error) => {
console.log('error,', error)
})
})