css 超实用的:empty —— 隐藏空元素、缺失字段智能提示

应用1：隐藏空元素

有时空元素会影响页面布局，通过:empty可以很方便地将它们隐藏。

<template>
  <ol>
    <li>一</li>
    <li></li>
    <li>三</li>
  </ol>
</template>

<style scoped>li:empty {
  display: none;
}</style>

注意事项：若是v-for循环，很多格式化插件在内容为空时，默认也会生成空格，则无法匹配:empty，解决方案是多加一层div

<template>
  <div class="bigBox">
    <div class="smallBox">1</div>
    <div class="smallBox">2</div>
    <div class="smallBox"></div>
    <div class="smallBox">4</div>
  </div>
</template>
<style scoped>.smallBox {
  height: 60px;
  width: 100px;
  background: red;
  color: white;
  text-align: center;
  line-height: 60px;
}
.smallBox:empty {
  display: none;
}
.bigBox {
  margin: 30px;
  width: 60%;
  display: flex;
  justify-content: space-around;
}</style>

应用2：缺失字段智能提示

<template>
  <div class="bigBox">
    <div class="smallBox" v-for="(item, index) in list" :key="index">
      <span class="content">{{ item }}</span>
    </div>
  </div>
</template>
<script>export default {
  data() {
    return {
      list: [1, 2, , 4],
    };
  },
};</script>

<style scoped>.bigBox {
  width: 60%;
  margin: 20px;
  display: flex;
  justify-content: space-around;
}
.smallBox {
  height: 60px;
  width: 100px;
  background: red;
  color: white;
  text-align: center;
  line-height: 60px;
}
.content:empty::before {
  content: "暂无编号";
}</style>

<template>
  <table border>
    <tr>
      <td>1</td>
      <td></td>
      <td>3</td>
    </tr>
  </table>
</template>


<style scoped>td {
  min-width: 100px;
  text-align: center;
}
td:empty::before {
  content: "暂无数据";
}</style>

类似的常用场景有：

.searchResult:empty::before {
   content: '没找到相关内容';
   display: block;
   line-height: 300px;
   text-align: center;
   color: gray;
}

.articleList:empty::before {
   content: '还没有发表任何文章';
   display: block;
   line-height: 300px;
   text-align: center;
   color: gray;
}

全局空元素样式的css

.empty:empty::before {
   content: '暂无数据';
   display: block;
   line-height: 300px;
   text-align: center;
   color: gray;
}