话不多说直接上代码

1，先引入onMounted

import { ref, getCurrentInstance,onMounted } from "vue";

2,写一下全屏函数

 const allScreen = ()=>{
        let domElement = document.documentElement;
    if (domElement.requestFullscreen) {
        domElement.requestFullscreen();
    } else if (domElement.mozRequestFullScreen) {
        domElement.mozRequestFullScreen();
    } else if (domElement.webkitRequestFullScreen) {
        domElement.webkitRequestFullScreen();
    }
    }

3,在onMounted里调用次函数

onMounted(()=>{
        console.log('进入页面')
        allScreen()
    })