script.js

const backdrop = document.getElementById('backdrop')
const video = document.getElementById('video')

Promise.all([
  faceapi.nets.tinyFaceDetector.loadFromUri('/models'),
  faceapi.nets.faceLandmark68Net.loadFromUri('/models'),
  faceapi.nets.faceRecognitionNet.loadFromUri('/models'),
  faceapi.nets.faceExpressionNet.loadFromUri('/models'),
]).then(startVideo)

function startVideo() {
  navigator.getUserMedia(
    { video: {} },
    stream => {
      video.srcObject = stream
      backdrop.srcObject = stream
    },
    err => console.error(err)
  )
}

video.addEventListener('play', () => {
  const canvas = faceapi.createCanvasFromMedia(video);
  document.body.append(canvas);
  const displaySize = { width: video.width, height: video.height };
  faceapi.matchDimensions(canvas, displaySize);
  setInterval(async () => {
    const detections = await faceapi.detectAllFaces(video,
      new faceapi.TinyFaceDetectorOptions()).withFaceLandmarks().withFaceExpressions()
    const resizedDetections = faceapi.resizeResults(detections, displaySize);
    canvas.getContext('2d').clearRect(0, 0, canvas.width, canvas.height)
    faceapi.draw.drawDetections(canvas, resizedDetections)
    faceapi.draw.drawFaceExpressions(canvas, resizedDetections)
    // faceapi.draw.drawFaceLandmarks(canvas, resizedDetections)

    console.log(detections)
  }, 1000)
})