vue中计算属性computed的特性和应用

特性：基于他们的依赖进行缓存，只要在他相关的依赖发生改变的时候，才会重新计算；

应用：基于template里面的{{ }}计算；处理props传值；处理后台返回的数据

<template>
  <div class="ComputedProps">
    {{ reservedMessage }}
    <ul>
      <li v-for="item in list" :key="item.id">
        <span>姓名：{{ item.name }}</span>
        <span>-------</span>
        <span>性别：{{ sexComputed(item.sex) }}</span>
      </li>
    </ul>
  </div>
</template>

<script>
export default {
  name: "ComputedProps",
  data() {
    return {
      message: "helloWorld",
      list: [
        {id: 1, name: "张三", sex: 0},
        {id: 2, name: "李四", sex: 1},
        {id: 3, name: "王五", sex: 0},
        {id: 4, name: "赵六", sex: 1},
        {id: 5, name: "钱七", sex: 1},
      ]
    }
  },
  computed: {
    //反转字符串
    reservedMessage() {
      return this.message.split("").reverse().join("")
    },
    //处理后台返回的数据
    sexComputed() {
      return (value) => {
        switch (value) {
          case 0:
            return "男";
          case 1:
            return "女"
        }
      }
    }
  }
}
</script>
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