Question

我有一系列日期，如何找到一周中最常见/第二/第三天等？我试过以下

moment(@date field).week()

但json日期数组怎么样？

Answer 1

有关详细信息，请参阅Map，Date.prototype.getDay()，Spread Syntax，Array.prototype.sort()，Destructured Assignment和Array.prototype.map()。

＆＃13;

// Input.
const dates = ['2018-04-19','2018-04-19','2018-04-19','2018-04-20','2018-04-24','2018-05-02','2018-05-02','2018-05-02']
const days = ['Sunday', 'Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday', 'Saturday']

// Occurences.
const occurrences = dates => [...dates.reduce((m, date) => {
  const day = days[new Date(date).getDay()]
  m.set(day, (m.get(day) || 0) + 1)
  return m
}, new Map)].sort((A, B) => B[1] - A[1])

// Output
const output = occurrences(dates)

// Proof.
console.log('With Counts', output)
console.log('Without Counts', output.map(([day]) => day))

＆＃13;

Answer 2

获取一周的日子
按频率对其进行排序（删除重复项）
将它们翻译成工作日字符串（您也可以使用moment或Intl.DateTimeFormat执行此操作）

＆＃13;

const dates = [
  '2018-04-19',
  '2018-04-19',
  '2018-04-19',
  '2018-04-20',
  '2018-04-24',
  '2018-05-02',
  '2018-05-02',
  '2018-05-02',
];

const daysOfWeek = dates.map(date => new Date(date).getDay());

// Now we have the days as numbers we can sort by frequency
// This function is from a google search: https://stackoverflow.com/a/3579651/414062
function sortByFrequency(array) {
  const frequency = {};

  array.forEach(value => frequency[value] = 0);
  const uniques = array.filter(value => ++frequency[value] == 1);
  return uniques.sort((a, b) => frequency[b] - frequency[a]);
}

const sortedDaysOfWeek = sortByFrequency(daysOfWeek);

// Now translate to weekday values
const weekdays = ['Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday', 'Saturday', 'Sunday'];
const weekdaysByFrequency = sortedDaysOfWeek.map(day => weekdays[day - 1]);

console.log(weekdaysByFrequency);

＆＃13;

如何找到一周中最多的一天？

2 个答案: