报错：Property or method “item“ is not defined on the instance but referenced during render.

前言：目前在敲项目，遇到的报错问题~

报错原因：

Property or method "item" is not defined on the instance but referenced during render. Make sure that this property is reactive, either in the data option, or for class-based components, by initializing the property. See: https://vuejs.org/v2/guide/reactivity.html#Declaring-Reactive-Properties.

found in

翻译报错：属性或方法“item”未在实例上定义，但在渲染期间被引用。通过初始化该属性，确保该属性是反应性的，无论是在数据选项中，还是对于基于类的组件。

简而言之，就是item未定义，但在渲染期间使用。 

错误代码/原代码：

 错误原因是识别了""双引号，里面应该写单引号

改完代码：

<el-col :span="16">
        <div class="num">
          <el-card
            v-for="item in countData"
            :key="item.name"
            :body-style="{ display:'flex', padding: 0 }"
          >
            <i
              class="icon"
              :class="`el-icon-${item.icon}`"
              :style="{ background: item.color }"
            >
            </i>
            <div class="detail">
              <p class="num">￥{{ item.value }}</p>
              <p class="txt">{{ item.name }}</p>
            </div>
          </el-card>
        </div>
</el-col>