electron/docs/fiddles/features/web-usb/main.js

const {app, BrowserWindow} = require('electron')
const e = require('express')
const path = require('path')

function createWindow () {
  const mainWindow = new BrowserWindow({
    width: 800,
    height: 600
  })
  
  let grantedDeviceThroughPermHandler

  mainWindow.webContents.session.on('select-usb-device', (event, details, callback) => {
    //Add events to handle devices being added or removed before the callback on
    //`select-usb-device` is called.
    mainWindow.webContents.session.on('usb-device-added', (event, device) => {    
      console.log('usb-device-added FIRED WITH', device)
      //Optionally update details.deviceList
    })
  
    mainWindow.webContents.session.on('usb-device-removed', (event, device) => {
      console.log('usb-device-removed FIRED WITH', device)
      //Optionally update details.deviceList
    })

    event.preventDefault()
    if (details.deviceList && details.deviceList.length > 0) {
      const deviceToReturn  = details.deviceList.find((device) => {
        if (!grantedDeviceThroughPermHandler || (device.deviceId != grantedDeviceThroughPermHandler.deviceId)) {
          return true
        }
      })
      if (deviceToReturn) {
        callback(deviceToReturn.deviceId)        
      } else {
        callback()
      }
    }
  })

  mainWindow.webContents.session.setPermissionCheckHandler((webContents, permission, requestingOrigin, details) => {
    if (permission === 'usb' && details.securityOrigin === 'file:///') {
      return true
    }
  })

  
  mainWindow.webContents.session.setDevicePermissionHandler((details) => {
    if (details.deviceType === 'usb' && details.origin === 'file://') {
      if (!grantedDeviceThroughPermHandler) {        
        grantedDeviceThroughPermHandler = details.device
        return true
      } else {
        return false
      }
    }
  })
  
  mainWindow.loadFile('index.html')
}

app.whenReady().then(() => {
  createWindow()
  
  app.on('activate', function () {
    if (BrowserWindow.getAllWindows().length === 0) createWindow()
  })
})

app.on('window-all-closed', function () {
  if (process.platform !== 'darwin') app.quit()
})