javascript - 如何从JSON中获取数据并与页面中的数据进行比较？

Question

下午好，请告诉我。我写了一个日历，现在我有一个 json 文件，其中包含事件信息，我希望事件的名称和事件类型准确地在记录的那一天显示在日历中。

因此，我需要:

1)从json点获取所有事件的start_at(事件日期)

2) 将 json 中的 start_at 项与日历中的日期进行比较

3) 如果第 2 段为真，则在末尾添加事件名称。

请帮我制作第1段和第2段。因为当我尝试自己制作它们时，我有这样的errors .

Code on GitHub

JSON代码:

{
  "meta": {
    "unremovable": [
      1
    ],
    "types": [
      [
        1,
        "public_holiday"
      ],
      [
        2,
        "day_off"
      ],
      [
        4,
        "birthday"
      ],
      [
        8,
        "meeting"
      ],
      [
        16,
        "other"
      ]
    ]
  },
  "events": [
    {
      "id": 211,
      "starts_at": "2019-03-08",
      "ends_at": "2019-03-08",
      "memo": "Международный женский день",
      "type": 3
    },
    {
      "id": 212,
      "starts_at": "2019-10-07",
      "ends_at": "2019-10-07",
      "memo": "День учителя",
      "type": 1
    },
    {
      "id": 213,
      "starts_at": "2019-10-14",
      "ends_at": "2019-10-14",
      "memo": "День защитника Украины",
      "type": 3
    },
    {
      "id": 214,
      "starts_at": "2019-10-18T14:00:00Z",
      "ends_at": "2019-10-18T15:00:00Z",
      "memo": "Созвон с Киевом",
      "type": 8
    },
    {
      "id": 215,
      "starts_at": "2019-10-18T09:00:00Z",
      "ends_at": "2019-10-18T13:15:00Z",
      "memo": "Велопрогулка",
      "type": 16
    },
    {
      "id": 216,
      "starts_at": "2019-10-22",
      "ends_at": "2019-10-22",
      "memo": "Гуляем в парке",
      "type": 16
    },
    {
      "id": 217,
      "starts_at": "2019-10-28",
      "ends_at": "2019-11-03",
      "memo": "Конференция",
      "type": 18
    }, 
    {
      "id": 218,
      "starts_at": "2019-11-03T21:43:00Z",
      "ends_at": "2019-11-03T21:43:00Z",
      "memo": "Самолёт домой",
      "type": 16
    },
    {
      "id": 219,
      "starts_at": "2019-11-11",
      "ends_at": "2019-11-11",
      "memo": "ДР",
      "type": 4
    }
  ]
}

日历代码:

<template>
  <div class="all">
    <div class="overflow-div">
      <div class="pagination">
        <div @click="prevPage" class="btn-left"><</div> 
        <p>{{ nameOfOneMonth }} {{ year }}</p>
        <div @click="nextPage" class="btn-right">></div> 
      </div>

        <div class="d_nameOfDays">
          <li v-for="day in nameOfDays" class="nameOfDays">{{ day }}</li>
        </div>
        <transition :name="nameOfClass" >
          <div :key="currentPage" class="fade_wrapper">
            <div v-for="(week, i) in getCalendar" class="d_day">
            <li v-for="day in week" class="li_day">
            <div class="day" 
               v-bind:class="{ 'grey': isAnotherMonth(i, day), 'currentDay': currentDayOnCalendar(day) }"
               >{{ day }}</div>
            </li>
            </div>
          </div>
        </transition>
    </div>
  </div> 
</template>

<script>
  import link from './Calendar_data.json';
export default {
  data(){
    return{
      currentPage: 0,
      namesOfMonths: ['January', 'February', 'March', 'April', 'May', 'June', 'July', 'August', 'September', 'October', 'November', 'December'],
      nameOfOneMonth: '',
      nameOfDays: ['Пн', 'Вт', 'Ср', 'Чт', 'Пт', 'Сб', 'Вс'],
      date: new Date(),
      isActive: true,
      year: '',
      nameOfClass: '',
      eventsData: []
    }
  },
  created: function(){
    fetch(link)
    // .then(response => response.json())
    .then(data => (
      this.eventsData = data
      ));
  },
  computed: {
    getCalendar(){
      return this.buildCalendar();
    }
  },
  mounted(){
    this.year = this.date.getFullYear();
    this.currentPage = this.date.getMonth();
    this.nameOfOneMonth = this.namesOfMonths[this.currentPage];
  },
  methods: {
    prevPage(){
      if (this.currentPage === 0) {
        this.currentPage = 12;
        this.year--;
      }
      this.nameOfClass = 'prev';
      this.currentPage--;
      this.nameOfOneMonth = this.namesOfMonths[this.currentPage];
    },
    nextPage(){
      if (this.currentPage === 11) {
        this.currentPage = -1;
        this.year++;
      }
      this.nameOfClass = 'next';
      this.currentPage++;
      this.nameOfOneMonth = this.namesOfMonths[this.currentPage];
    },
    isAnotherMonth(weekIndex, dayNumber) {
      if(weekIndex === 0 && dayNumber > 15) {
        return true
      }
      if (weekIndex === 4 && dayNumber < 15) {
        return true
      }
      if (weekIndex === 5 && dayNumber < 15) {
        return true
      }
      return false
    },
    currentDayOnCalendar(dayNumber){
      if(this.currentPage === this.date.getMonth() && 
        dayNumber === this.date.getDate() && 
        this.year === this.date.getFullYear()){
        return true
      }
      return false
    },
    getYear(){
      this.year = this.date.getFullYear();
    },
    getLastDayOfMonth(month) { 
      let dateDaysInMonth = new Date(this.year, month + 1, 0);
      return dateDaysInMonth.getDate();
    },
    getNumberOfFirstDayInMonth(month){ 
      let dateFirstDayInMonth = new Date(this.year, month, 1);
      return dateFirstDayInMonth.getDay();
    },
    buildCalendar(){
      let massOfMonth = [];
      let massOfEvents = this.eventsData.events;
      for (let months = 0; months < 12; months++){
        massOfMonth.push(months);
        massOfMonth[months] = [];
        for ( let daysInMonth = 1; daysInMonth <= this.getLastDayOfMonth(months); daysInMonth++){
          massOfMonth[months].push(daysInMonth);
          massOfMonth[months][daysInMonth] = [];
          for(let m = 0; m <=massOfEvents.length; m++){
            let v = massOfEvents[m].starts_at;
            let d = new Date(v);
            console.log(m)
          }
        }
        if(this.getNumberOfFirstDayInMonth(months) > 0){
          let t = this.getLastDayOfMonth(months-1) + 1;
          for(let b = 0; b <= this.getNumberOfFirstDayInMonth(months) - 2; b++){
            t--;
            massOfMonth[months].unshift(t)
          }
        }else if(this.getNumberOfFirstDayInMonth(months) === 0){
          let t = this.getLastDayOfMonth(months-1) + 1;
          for(let nulldays = 0; nulldays <= 5; nulldays++){
            t--;
            massOfMonth[months].unshift(t);
          }
        }
        if((this.getNumberOfFirstDayInMonth(months) === 0 || 
          this.getNumberOfFirstDayInMonth(months) === 6) &&
          (this.getNumberOfFirstDayInMonth(months + 1) > 1 &&
          this.getNumberOfFirstDayInMonth(months + 1) < 3)){
          let t = 0;
          for(let q = this.getNumberOfFirstDayInMonth(months + 1); q <= 7; q++){
            t++;
            massOfMonth[months].push(t);
          }
        } else{
          let t = 0;
          for(let q = this.getNumberOfFirstDayInMonth(months + 1); q <= 14; q++){
            t++;
            massOfMonth[months].push(t);
          }
        }
      }
      var longArray = massOfMonth[this.currentPage];
      var size = 7;

      var newArray = new Array(Math.ceil(longArray.length / size)).fill("")
          .map(function() { 
            return this.splice(0, size) 
          }, longArray.slice());
        return newArray; 
    }
  }
};
</script>

Answer 1

发生这种情况是因为 buildCalendar 在任何获取请求完成之前被调用。

let MassOfEvents = this.eventsData.events; eventsData 是一个空数组，因此其属性 events 未定义。因此，无法读取其长度 (massOfEvents.length)。

重构您的 buildCalendar 函数，以便它设置一些数据，例如处理的事件:

data(){
    return{
        currentPage: 0,
        ...
        eventsData: [],
        processedEvents: []
    }
  },
  ...
  methods: {
     buildCalendar () {
        ...
        ...
        this.processedEvents = newArray;
     }
  }

...并在模板中使用processedEvents而不是getCalendar；像这样:

<div v-for="(week, i) in processedEvents" class="d_day">

我并没有真正检查你的 1...3 点，我只是修复了你的语法并使其有望正常工作。