const { createApp, ref, onMounted } = Vue;

function useCourses() {
  const courses = ref([]);
  const loading = ref(true);
  const error = ref("");

  async function loadCourses() {
    // 任务：
    // 1. 模拟异步请求
    // 2. 成功时给 courses 赋值
    // 3. 失败时给 error 赋值
    // 4. 最后把 loading 设为 false
  }

  return {
    courses,
    loading,
    error,
    loadCourses,
  };
}

createApp({
  setup() {
    const { courses, loading, error, loadCourses } = useCourses();

    onMounted(() => {
      // 任务：页面挂载后调用 loadCourses
    });

    return {
      courses,
      loading,
      error,
    };
  },
}).mount("#app");