javascript - 如何使用vue js过滤日期范围？

Question

我正在学习 vue.js，并且正在尝试使用范围日期的过滤器功能。场景是:先按类型过滤，再按日期范围过滤(有开始日期和结束日期)。选择结束日期后将显示结果。我已经创建了第一个过滤器，它是 type，它可以工作。我已经搜索了各种日期范围的方法，但仍然找不到合适的方法。如何使用 computed 或 methods 过滤日期范围？如果有人知道，请你一步步告诉我好吗？

new Vue({
  el: '#app',
  data: {
    selectedType: '',
    startDate:null,
    endDate:null,
    items: [
      {
        name: 'Nolan',
        type: 'mercedes',
        year: '2020',
        country: 'england',
        date: '08/01/2020'
      },
      {
        name: 'Edgar',
        type: 'bmw',
        year: '2020',
        country:'belgium',
        date: '08/11/2020'
      },
      {
        name: 'John',
        type: 'bmw',
        year: '2019',
        country: 'england',
        date: '08/21/2020'
      },
      {
        name: 'Axel',
        type: 'mercedes',
        year: '2020',
        country: 'england',
        date: '08/01/2020'
      }
    ]
  },
  computed: {
    filterItem: function () {
      
      let filterType = this.selectedType
      if (!filterType) return this.items;  // when filterType not selected

      let startDate = this.startDate && new Date(this.startDate);
      let endDate = this.endDate && new Date(this.endDate);
      
      return this.items.filter(item => {
        return item.type == filterType;
      }).filter(item => {
        const itemDate = new Date(item.date)
        if (startDate && endDate) {
          return startDate <= itemDate && itemDate <= endDate;
        }
        if (startDate && !endDate) {
          return startDate <= itemDate;
        }
        if (!startDate && endDate) {
          return itemDate <= endDate;
        }
        return true;  // when neither startDate nor endDate selected
      })
      
    }
  }
})

.list-item {
  margin-top: 50px;
}

#app {
  position: relative;
  padding-bottom: 200px;
}

span {
  margin: 0 15px;
  cursor: pointer;
}

.filter-box {
  margin-top: 15px;
}

.card {
  box-shadow: 0px 10px 16px rgba(0, 0, 0, 0.16);
  width: 400px;
  padding: 20px 30px;
  margin-bottom: 30px;
}

button {
  background-color: #1cf478;
  border: none;
  padding: 10px 25px;
  font-weight: bold;
  border-radius: 15px;
}

select,input {
  border: none;
  padding: 10px 15px;
  background-color: #c1c1c1;
  border-radius: 10px;
}

<script src="https://cdnjs.cloudflare.com/ajax/libs/vue/2.5.17/vue.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>

<div id="app">
  <label for="">Type</label>
  <select v-model="selectedType">
    <option value="" disabled selected hidden>Type</option>
    <option value="mercedes">Mercedes</option>
    <option value="bmw">BMW</option>
  </select>
  
  <label for="">From</label>
  <input type="date" v-model="startDate">
  
  <label for="">To</label>
  <input type="date" v-model="endDate">
  
  <div class="list-item" v-for="item in filterItem">
    <div class="card">
      <p>Name: {{ item.name }}</p>
      <p>Car: {{ item.type }}</p>
      <p>Date: {{ item.date }}</p>
      <p>Country: {{ item.country }}</p>
    </div>
  </div>
</div>

Answer 1

修复方法如下:

1. 创建 startDate 和 endDate 作为 Date。但是，请注意日期选择器使用 ISO 字符串格式 (yyyy-mm-dd)，即 UTC。数据包含特定于区域设置的日期 (mm/dd/yyyy)，因此 Date 会使用本地时区解析字符串。我们需要规范化日期，以便比较具有相同时区偏移量的日期(首选本地):

   methods: {
     localizeDate(date) {
       if (!date || !date.includes('-')) return date
       const [yyyy, mm, dd] = date.split('-')
       return new Date(`${mm}/${dd}/${yyyy}`)
     }
   }
   

   let startDate = this.localizeDate(this.startDate);
   let endDate = this.localizeDate(this.endDate);
   

2. if-else 中的日期比较明确检查是否为 null，但它们的值不会是 null 因为您正在实例化 Date 对象。通过步骤 1 中的更新，日期值为 Date 或 false，因此您可以更新比较以检查是否存在虚假值而不是 null:

   if (startDate && endDate) {/*...*/}
   if (startDate && !endDate) {/*...*/}
   if (!startDate && endDate) {/*...*/}
   

3. selectedType 永远不会是 null，但您可以检查它是否为假以确定类型是否未指定。在这种情况下，您可以只返回原始数组以避免不必要地调用 Array.prototype.filter:

   const itemsByType = filterType ? this.items.filter(item => item.type === filterType) : this.items
   

4. 由于您想将日期显示为MMM dd, yyyy，您可以使用Intl.DateTimeFormat 的“长”日期样式在组件方法中，并从模​​板中调用它:

   methods: {
     formatDate(date) {
       return new Intl.DateTimeFormat('en-US', { dateStyle: 'long' }).format(new Date(date))
     }
   }
   

   <p>Date: {{ formatDate(item.date) }}</p>
   

new Vue({
  el: '#app',
  data: {
    selectedType: '',
    startDate:null,
    endDate:null,
    items: [
      {
        name: 'Nolan',
        type: 'mercedes',
        year: '2020',
        country: 'england',
        date: '08/01/2020'
      },
      {
        name: 'Edgar',
        type: 'bmw',
        year: '2020',
        country:'belgium',
        date: '08/11/2020'
      },
      {
        name: 'John',
        type: 'bmw',
        year: '2019',
        country: 'england',
        date: '08/21/2020'
      },
      {
        name: 'Axel',
        type: 'mercedes',
        year: '2020',
        country: 'england',
        date: '08/01/2020'
      }
    ]
  },
  computed: {
    filterItem() {
      let filterType = this.selectedType;
      let startDate = this.localizeDate(this.startDate);
      let endDate = this.localizeDate(this.endDate);
      
      const itemsByType = filterType ? this.items.filter(item => item.type === filterType) : this.items
      return itemsByType
        .filter(item => {
          const itemDate = new Date(item.date)
          if (startDate && endDate) {
            return startDate <= itemDate && itemDate <= endDate;
          }
          if (startDate && !endDate) {
            return startDate <= itemDate;
          }
          if (!startDate && endDate) {
            return itemDate <= endDate;
          }
          return true;
        })
    }
  },
  methods: {
    localizeDate(date) {
      // Date picker uses ISO format (yyyy-mm-dd), which is UTC. The data
      // contains locale specific date strings (mm/dd/yyyy), which `Date`
      // parses with local time-zone offset instead of UTC. Normalize the
      // ISO date so we're comparing local times.
      if (!date || !date.includes('-')) return date
      const [yyyy, mm, dd] = date.split('-')
      return new Date(`${mm}/${dd}/${yyyy}`)
    },
    formatDate(date) {
      return new Intl.DateTimeFormat('en-US', { dateStyle: 'long' }).format(new Date(date))
    }
  }
})

.list-item {
  margin-top: 50px;
}

.card {
  box-shadow: 0px 10px 16px rgba(0, 0, 0, 0.16);
  width: 400px;
  padding: 20px 30px;
  margin-bottom: 30px;
}

select,input {
  border: none;
  padding: 10px 15px;
  background-color: #c1c1c1;
  border-radius: 10px;
}

<script src="https://cdnjs.cloudflare.com/ajax/libs/vue/2.5.17/vue.js"></script>

<div id="app">
  <label for="">Type</label>
  <select v-model="selectedType">
    <option value="" disabled selected hidden>Type</option>
    <option value="mercedes">Mercedes</option>
    <option value="bmw">BMW</option>
  </select>
  
  <label for="">From</label>
  <input type="date" v-model="startDate">
  
  <label for="">To</label>
  <input type="date" v-model="endDate">
  
  <div class="list-item" v-for="item in filterItem">
    <div class="card">
      <p>Name: {{ item.name }}</p>
      <p>Car: {{ item.type }}</p>
      <p>Date: {{ formatDate(item.date) }}</p>
      <p>Country: {{ item.country }}</p>
    </div>
  </div>
</div>