安装Vuex4.0以上版本

npm install vuex@4.0.0 -s

在​​src​​​目录下新建​​store/index.js​​文件夹

import {
    createStore
} from 'vuex';

export default createStore({
    state: {
        num: 123
    }
});

在​​main.js​​引入

import {
    createApp
} from 'vue'
import App from './App.vue'
import vuex from './store'
const app = createApp(App)
app.use(vuex)
app.mount('#app')

组件引入

<script>
import { onMounted } from "vue";
import { useStore } from "vuex";
export default {
  setup() {
    const store = useStore();
    onMounted(() => {
      console.log(store.state.num);
    });
  },
};
</script>