获取所有设备【已解决】

queryDevices.js

// ***SOLVED***
var globalStream;
navigator.mediaDevices.getUserMedia({
        audio: true,
        video: true
      })
.then(function(stream) {
  globalStream = stream;
})
.catch(function(err) {
      console.log(err)
});

function stopStream() {
    if (!globalStream) return;
    globalStream.getAudioTracks().forEach(function(track) {
        track.stop();
    });
    globalStream.getVideoTracks().forEach(function(track) {
        track.stop();
    });
    globalStream = null;
}