在使用TS时,组件需要用defineComponent,不用CompositionApi,使用this.$store报错是ts类型检测报错。没有$store的类型声明。解决办法如下 
ts
import { ElMessage } from 'element-plus';
import type { Store } from 'vuex';
import { IMessage } from 'element-plus/lib/el-message/src/types';
declare module '@vue/runtime-core' {
  interface ComponentCustomProperties {
    $store: Store<any>;
    $message: IMessage;
  }
}
const app = createApp(App);
app.use(store).use(router);
app.config.globalProperties.$store = store;
app.config.globalProperties.$message = ElMessage;
app.mount('#app');




