某个dom全屏或者整体页面全屏

//如果dom没有就让整个页面全屏
const full = document.querySelector('#box') || document.documentElement

if (full.RequestFullScreen) {
  full.RequestFullScreen()

  //兼容Firefox
} else if (full.mozRequestFullScreen) {
  full.mozRequestFullScreen()

  //兼容Chrome, Safari and Opera等
} else if (full.webkitRequestFullScreen) {
  full.webkitRequestFullScreen()

  //兼容IE/Edge
} else if (full.msRequestFullscreen) {
  full.msRequestFullscreen()
}