<template>
 <div>
   <a-button type="primary" @click="screen">全屏</a-button>
 </div>
</template>

 data() {
  return {
   fullscreen: false
  };
 },

screen() {
   let element = document.documentElement;
   if (this.fullscreen) {
    if (document.exitFullscreen) {
     document.exitFullscreen();
    } else if (document.webkitCancelFullScreen) {
     document.webkitCancelFullScreen();
    } else if (document.mozCancelFullScreen) {
     document.mozCancelFullScreen();
    } else if (document.msExitFullscreen) {
     document.msExitFullscreen();
    }
   } else {
    if (element.requestFullscreen) {
     element.requestFullscreen();
    } else if (element.webkitRequestFullScreen) {
     element.webkitRequestFullScreen();
    } else if (element.mozRequestFullScreen) {
     element.mozRequestFullScreen();
    } else if (element.msRequestFullscreen) {
     // IE11
     element.msRequestFullscreen();
    }
   }
   this.fullscreen = !this.fullscreen;
  },

npm install --save screenfull

import screenfull from ‘screenfull'

<template>
   <div>
     <a-button type="primary" @click="screen">全屏</a-button>
   <div>
</template>

 data() {
  return {
   fullscreen: false
  };
 },

screen() {
   // 如果不允许进入全屏，发出不允许提示
   if (!screenfull.enabled) {
    this.$message("您的浏览器不能全屏");
    return false;
   }
   screenfull.toggle();
   this.$message.success("全屏啦");
  },