screefull全屏

1.安装
npm install screenfull@5 --save

2.使用
import screenfull from "screenfull";

screenfull.isFullscreen; // 当前页面是否全屏
screenfull.isEnabled; // 当前浏览器是否支持全屏

screenfull.request(); // 全屏
screenfull.exit(); // 退出全屏
screenfull.toggle(); // 全屏切换

 screenfull.toggle(this.$refs.testTag);//指定元素全屏