判断iPhoneX

if (/iphone/gi.test(navigator.userAgent) && (screen.availWidth === 375) && (screen.availHeight === 812)) {
  alert('iPhoneX')
  if ((window.innerHeight == '375') && (window.innerWidth == '812')) {
    alert('水平摆放')
  } else {
    alert('垂直摆放')
  }
}