用vue3 写一个全局的loading组件

以下是一个基本的全局加载组件示例，使用Vue 3和Composition API编写：

<template>
  <div v-if="loading" class="loading-overlay">
    <div class="loading-spinner"></div>
  </div>
</template>

<script>
import { ref } from 'vue';

export default {
  setup() {
    const loading = ref(false);

    const showLoading = () => {
      loading.value = true;
    };

    const hideLoading = () => {
      loading.value = false;
    };

    return {
      loading,
      showLoading,
      hideLoading,
    };
  },
};
</script>

<style>
.loading-overlay {
  position: fixed;
  top: 0;
  left: 0;
  z-index: 9999;
  width: 100%;
  height: 100%;
  background-color: rgba(0, 0, 0, 0.5);
  display: flex;
  justify-content: center;
  align-items: center;
}

.loading-spinner {
  border-radius: 50%;
  width: 30px;
  height: 30px;
  border: 4px solid rgba(255, 255, 255, 0.3);
  border-top-color: #fff;
  animation: spin 1s ease-in-out infinite;
}

@keyframes spin {
  to {
    transform: rotate(360deg);
  }
}
</style>

可以将此组件放在App.vue中，以便在整个应用程序中使用：

<template>
  <div id="app">
    <loading v-if="loading" />
    <router-view />
  </div>
</template>

<script>
import Loading from './components/Loading.vue';

export default {
  components: {
    Loading,
  },
  data() {
    return {
      loading: false,
    };
  },
  created() {
    this.$on('loading:show', () => {
      this.loading = true;
    });
    this.$on('loading:hide', () => {
      this.loading = false;
    });
  },
};
</script>

要显示加载中状态，请在需要的组件中调用以下代码：

this.$emit('loading:show');

要隐藏加载中状态，请调用以下代码：

this.$emit('loading:hide');
``