toggleFullscreen() {
  if (!screenfull.enabled) {
   this.$message({
    message: 'you browser can not work',
    type: 'warning'
   })
   return false
  }
  screenfull.toggle()
}

<script>
import screenfull from 'screenfull'
export default {
 data () {
   return {
    isFullscreen: false
   }
  }，
 methods: {
  /**
   * 全屏事件
   */
  screenfull() {
   if (!screenfull.enabled) {
    this.$message({
     message: 'Your browser does not work',
     type: 'warning'
    })
    return false
   }
   screenfull.toggle()
   this.isFullscreen = true
  },
  /**
   * 是否全屏并按键ESC键的方法
   */
  checkFull() {
   var isFull = document.fullscreenEnabled || window.fullScreen || document.webkitIsFullScreen || document.msFullscreenEnabled
   // to fix : false || undefined == undefined
   if (isFull === undefined) {
     isFull = false
   }
   return isFull
  }
 },
 mounted() {
   window.onresize = () => {
      // 全屏下监控是否按键了ESC
      if (!this.checkFull()) {
       // 全屏下按键esc后要执行的动作
       this.isFullscreen = false
      }
     }
    }
}
</script>