main.js

'use strict'
const NodeWebcam = require( "node-webcam" ),
      vision = require('google-cloud').vision,
      notifier = require('node-notifier')

const visionClient = vision({
  projectId:  process.env.GCLOUD_PROJECT,
  keyFilename: './keyfile.json'
})

const cam = NodeWebcam.create({
    width: 1280,
    height: 720,
    delay: 0,
    quality: 100,
    output: "jpeg",
    verbose: true
})

const notify = (message) => {
  notifier.notify({
    title: "表情検知",
    message: message
  })
}

const detect = (path) => {
  visionClient.detectFaces(path, function(err, faces) {
    console.log("detect result")
    if (err) {
      console.log(err)
    } else if (faces && faces.length > 0) {
      const face = faces[0]
      console.log(face)
      if (face.sorrow) {
        notify('😣悲しみの表情を検知しました。')
      } else if (face.anger) {
        notify('😠怒りの表情を検知しました。')
      } else if (face.joy) {
        notify('😁喜びの表情を検知しました。')
      }
    }
  })
}

setInterval(() => {
  const path = `/tmp/face_picture.jpg`

  cam.capture(path, (err) => {
    if (err) {
      console.log( err )
    } else {
      detect(path)
    }
  })

}, 3000)

package.json

{
  "name": "face",
  "version": "1.0.0",
  "description": "",
  "main": "main.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "author": "",
  "license": "ISC",
  "dependencies": {
    "google-cloud": "^0.46.1",
    "node-cloud-vision-api": "^0.2.0",
    "node-notifier": "^5.0.2",
    "node-webcam": "^0.3.4"
  }
}