JS全屏--requestFullscreen()

document.addEventListener("keydown", function(e) {
    if (e.keyCode == 13) {
      toggleFullScreen();
    }
}, false);

function toggleFullScreen() {
   if (!document.fullscreenElement) {
      document.documentElement.requestFullscreen();
  } else {
    if (document.exitFullscreen) {
      document.exitFullscreen();
    }
  }
}

1. document下没有requestFullscreen
2. requestFullscreen方法只能由用户触发，比如：在onload事件中不能触发、Vue的mounted内不能触发