javascript - 累计每小时时间范围内的记录数

Question

我会尽我所能解释这一点。

我有一系列独特的日期，格式为 DD/MM/YYYY，如下所示:

const sortDates = [
'14/04/2018',
'12/04/2018',
'10/04/2018',
]

然后我有一个包含以下信息的对象数组。

const bookings = [
  { bookingStart: '2018-04-14 00:30:00' },
  { bookingStart: '2018-04-14 00:42:00' },
  { bookingStart: '2018-04-14 13:35:00' },
  { bookingStart: '2018-04-12 12:30:00' },
];

我想要实现的目标是每天按小时查找和分组数据。示例如下:

const groupedData = [{
  date: '2018-04-14',
  period : {
     startTime: '00:00',
     endTime: '00:59',
     total: 2, //total bookings found 2018/04/14 00:00 -> 00:59
  },
  date: '2018-04-14',
  period : {
     startTime: '01:00',
     endTime: '01:59',
     total: 0,  //total bookings found 2018/04/14 01:00 -> 01:59
  },
  ...etc
}

但是我有点卡住了。我目前的代码如下，不确定返回语句应该如何:

const groupData = sortDates.map((date) => {
  for (let i = 0; i <= 23; i += 1) {
    const startTime = new Date(date);
    const endTime = new Date(date);
    startTime.setHours(i);
    startTime.setMinutes(0);
    startTime.setSeconds(0);
    startTime.setMilliseconds(0);
    endTime.setHours(i);
    endTime.setMinutes(59);
    endTime.setSeconds(0);
    endTime.setMilliseconds(0);
    bookings.map((booking) => {
      const dateTime = new Date(booking.bookingStart);
      if (startTime.getTime() >= dateTime.getTime()
      && dateTime.getTime() <= endTime.getTime()) {
        return {
          date: dateTime,
        };
      }
      return null;
    });
  }
  return null;
});

甚至不确定这是否是最好或最快的方法，但我如何以我想要的格式返回？有更快的选择吗？

Answer 1

我会避免完全弄乱日期，而只是比较字符串:

const hmsToHM = hms => hms.match(/^\d\d:\d\d/)[0];
const bookings = [
  { bookingStart: '2018-04-14 00:30:00' },
  { bookingStart: '2018-04-14 00:42:00' },
  { bookingStart: '2018-04-14 00:42:22' },
  { bookingStart: '2018-04-14 00:42:44' },
  { bookingStart: '2018-04-14 13:35:00' },
  { bookingStart: '2018-04-14 00:30:55' },
  { bookingStart: '2018-04-12 12:30:00' },
];
const groupedData = bookings.reduce((groupedData, { bookingStart }) => {
  const [date, time] = bookingStart.split(' ');
  const startHourMin = hmsToHM(time);

  const groupedObj = (() => {
    const foundObj = groupedData
      .find(({ date: findGroupDate, period: {startTime }}) => {
        const findStartHourMin = hmsToHM(startTime);
        return findGroupDate === date && findStartHourMin === startHourMin;
      });
    if (foundObj) return foundObj;
    const newObj = { date, period: {
      startTime: startHourMin + ':00',
      endTime: startHourMin + ':59',
      total: 0,
    }}
    groupedData.push(newObj);
    return newObj;  
  })();

  groupedObj.period.total++;
  return groupedData;
}, []);
console.log(groupedData);