vue3中怎么实现定义全局变量

app.config.globalProperties.$systemId = "10"

import { getCurrentInstance } from "vue";const systemId = getCurrentInstance()?.appContext.config.globalProperties.$systemIdconsole.log(systemId);//控制台可以看到输出了10

// 之前(Vue 2.x)Vue.prototype.$http = () => {} // 之后(Vue 3.x)const app = Vue.createApp({})app.config.globalProperties.$http = () => {}

import { getCurrentInstance, onMounted } from "vue";export default {  setup( ) {    const { ctx } = getCurrentInstance(); //获取上下文实例，ctx=vue2的this    onMounted(() => {      console.log(ctx, "ctx");      ctx.http();    });  },};

import { getCurrentInstance } from 'vue'export default ({  name: '',  setup(){    const { proxy } = getCurrentInstance() // 使用proxy代替ctx，因为ctx只在开发环境有效    onMounted(() => {      console.log(proxy, "proxy");      proxy.http();    });  }})