将 Vue 2 迁移到 Vue 3，类型错误：Vue 不是构造函数

Question

如何将 Vue 2 语法迁移到 Vue 3，因为我收到以下错误：类型错误：Vue 不是构造函数。现在我正在使用 Vue 3：let app;firebase.auth().onAuthStateChanged(user => {  console.log("user", user);  if (!app) {    app = new Vue({      router,      store,      render: h => h(App)    }).$mount("#app");  }});到import { createApp } from "vue";const app = createApp({});app.mount("#app");

Answer 1

Vue 3、Vuex 4、Vue Router 4 中的代码等效于：

import { createApp } from 'vue'

import store from './store'

import router from './router'

import App from './App.vue'

let app;

firebase.auth().onAuthStateChanged(user => {

  console.log("user", user);

  app = createApp(App);

  app.use(store);

  app.use(router);

  app.mount("#app");

});

store.js中的存储语法略有不同：

import { createStore } from 'vuex'

// now uses `createStore`

export default createStore({ 

  state: {},

  getters: {},

  mutations: {},

  actions: {}

})

以及router.js中的路由器：

import { createWebHistory, createRouter } from "vue-router";

import Home from "@/views/Home.vue";

import About from "@/views/About.vue";

const routes = [

  {

    path: "/",

    name: "Home",

    component: Home,

  },

  {

    path: "/about",

    name: "About",

    component: About,

  },

];

const router = createRouter({

  history: createWebHistory(),

  routes,

});

export default router;