如何查找一个月内缺少的日期范围[NODE JS]？

Question

例如，用户选择01/2020到01/2020的月份范围来过滤上载的报告，而他的报告日期范围是06/01/2020到13/01/2020。这不符合要求，因为它缺少完成该月的日期范围（从01/01/2020到06/01/2020以及从13/01/2020到31/01/2020）。因此，我需要找到该月的缺失日期范围，并要求用户上传该时间段的报告。我已经尝试通过查找给定月份（01/2020-01/2020）（filterDateArray）中所有天的数组与报告具有的天的数组（06/01/2020-13）的差来获取缺少日期的数组/ 01/2020）（existingDateArray）：

filterDateArray.filter(x => !existingDateArray.includes(x))

这将返回月份中所有缺少的日期的数组

[
  '01/01/2020', '02/01/2020',
  '03/01/2020', '04/01/2020',
  '05/01/2020', '14/01/2020',
  '15/01/2020', '16/01/2020',
  '17/01/2020', '18/01/2020',
  '19/01/2020', '20/01/2020',
  '21/01/2020', '22/01/2020',
  '23/01/2020', '24/01/2020',
  '25/01/2020', '26/01/2020',
  '27/01/2020', '28/01/2020',
  '29/01/2020', '30/01/2020',
  '31/01/2020'
]

问题是，我无法为该数组中的缺失报告获取日期范围。预期结果的日期范围应为01/01/2020至06/01/2020和13/01/2020至31/01/2020。这意味着用户应至少再上传两个报告才能完成月份

Answer 1

在我看来，缺少的范围是：

• 01/01/2020-05/01/2020
• 14/01/2020-31/01/2020。

您可以创建一个函数来根据日期数组创建范围，该日期范围从第一个日期的第一个范围开始和结束。然后，它检查每个后续日期是否是第二天。如果不是，则前一个日期是该范围的最后一天，当前日期是下一个范围的第一天，依此类推。当到达数组末尾时，它将关闭当前范围（如果有）。

例如修改后的数据以包括单日范围：

// parse d/m/y to Date
function datesToRanges(dates) {
  let parse = s => {
    let [d, m, y] = s.split(/\D/);
    return new Date(y, m-1, d);
  }
  // Add 1 day to a date, return the date
  let add = d => {
    d.setDate(d.getDate() + 1);
    return d;
  }
  // Pad single digit numbers with leading zero
  let z = n => (n<10?'0':'') + n;
  // Format Date as d/m/y
  let format = d => `${z(d.getDate())}/${z(d.getMonth()+1)}/${d.getFullYear()}`;
  
  // Initialise variables
  let startRange, endRange, endPlusOne, ranges = [];
      
  // Loop over dates
  for (let i=0, iLen=dates.length; i < iLen; i++) {
  
    // Initialise start and end range if not set
    if (!startRange) {
      startRange = dates[i];
      endRange = startRange;
      i++;
    }
  
    // Get a string for endRange + 1 day
    endPlusOne = format(add(parse(endRange)));
    
    // If current == next date and there are more dates
    // to come, update endRange
    if (endPlusOne == dates[i] && dates[i+1]) {
      endRange = endPlusOne;
      
    // Otherwise, at end of current range
    // Write range to result, update start and end
    // If at end of array, write last range
    } else {
      ranges.push(startRange + ' - ' + endRange);
      startRange = dates[i];
      endRange = startRange;

      // Check if at end of dates array and have started a range
      if (!dates[i+1] && startRange) {
        ranges.push(startRange + ' - ' + endRange);
      }
    }
  }
  return ranges;
}

// data
let dates = ['01/01/2020',                           // Single date at start
             '03/01/2020','04/01/2020','05/01/2020', // 3 day range
             '14/01/2020','15/01/2020','16/01/2020', // 7 day range
             '17/01/2020','18/01/2020','19/01/2020',
             '20/01/2020',
             '22/01/2020',                           // Single date range
             '24/01/2020','25/01/2020','26/01/2020', // 6 day range
             '27/01/2020','28/01/2020','29/01/2020',
             '31/01/2020'];                          // Single date at end

console.log(datesToRanges(dates).join('\n'));