function launchFullscreen(element) {
 if (element.requestFullscreen) {
  element.requestFullscreen()
 } else if (element.mozRequestFullScreen) {
  element.mozRequestFullScreen()
 } else if (element.msRequestFullscreen) {
  element.msRequestFullscreen()
 } else if (element.webkitRequestFullscreen) {
  element.webkitRequestFullScreen()
 }
}

launchFullscreen(document.documentElement) // 整个页面进入全屏
launchFullscreen(document.getElementById("id")) //某个元素进入全屏

function exitFullscreen() {
 if (document.exitFullscreen) {
  document.exitFullscreen()
 } else if (document.msExitFullscreen) {
  document.msExitFullscreen()
 } else if (document.mozCancelFullScreen) {
  document.mozCancelFullScreen()
 } else if (document.webkitExitFullscreen) {
  document.webkitExitFullscreen()
 }
}
exitFullscreen()

document.addEventListener("fullscreenchange", function (e) {
 if (document.fullscreenElement) {
  console.log('进入全屏')
 } else {
  console.log('退出全屏')
 }
})