javascript - 数组元素之间的过滤

Question

我有一个日期数组:

const dates = ['date1', 'date2', 'date3', 'date4', 'date5'];

还有一个函数，它获取两个值，如果两个日期在同一周，则返回 true

function isSameWeek(a,b){
// some code
 return true or false;
}

我想过滤dates数组，使其所有值都不在同一周(每周一个)。

例如，如果 isSameWeek('date1', 'date2')=true ，则过滤后的数组应为 filtered=['date1', 'date3', 'date4', '日期5']

感谢您的帮助:)

Answer 1

如果日期已排序，则只需一次即可完成:

// monkey patching here for example sake (ignore this)
Date.prototype.getWeekNumber = function() {
  var d = new Date(Date.UTC(this.getFullYear(), this.getMonth(), this.getDate()));
  var dayNum = d.getUTCDay() || 7;
  d.setUTCDate(d.getUTCDate() + 4 - dayNum);
  var yearStart = new Date(Date.UTC(d.getUTCFullYear(),0,1));
  return Math.ceil((((d - yearStart) / 86400000) + 1)/7);
}

const isSameWeek = (a, b) => a.getWeekNumber() == b.getWeekNumber();

function getWeeklyDates(dates)
{
  // can remove the sort() if already sorted
  dates.sort((a, b) => a - b)
  // filter out in a single pass
  return dates.filter((date, index) => {
    return index > 0 ? !isSameWeek(date, dates[index - 1]) : true; // not in the same week
  });
}

const dates = [
  new Date('2020-01-01'),
  new Date('2020-02-01'),
  new Date('2020-01-03'),
  new Date('2020-03-05'),
  new Date('2020-03-03')
];

console.log(getWeeklyDates(dates));