如何使用日期-fns查找星期几的最近日期

Question

我希望能够根据具有date-fns的当前日期找出过去最近的星期几。假设我需要根据当前日期查找过去的最近的星期五，星期三，星期四等。

我查看了文档，仅看到了我认为可能有帮助的两个拖曳方法https://date-fns.org/docs/closestTo和https://date-fns.org/v1.29.0/docs/getDay，但缺少了我所寻找的方法。

有什么想法吗？

Answer 1

const { getISODay, addDays } = require('date-fns');

function getClosestDayOfLastWeek(dayOfWeek, fromDate = new Date()) {
    // follow the getISODay format (7 for Sunday, 1 for Monday)
    const dayOfWeekMap = {
        Mon: 1,
        Tue: 2,
        Wed: 3,
        Thur: 4,
        Fri: 5,
        Sat: 6,
        Sun: 7,
    };

    // -7 means last week
    // dayOfWeekMap[dayOfWeek] get the ISODay for the desired dayOfWeek

    // e.g. If today is Sunday, getISODay(fromDate) will returns 7
    // if the day we want to find is Thursday(4), apart from subtracting one week(-7),
    // we also need to account for the days between Sunday(7) and Thursday(4)
    // Hence we need to also subtract (getISODay(fromDate) - dayOfWeekMap[dayOfWeek])
    const offsetDays = -7 - (getISODay(fromDate) - dayOfWeekMap[dayOfWeek]);

    return addDays(fromDate, offsetDays);
}

console.log(getClosestDayOfLastWeek('Mon'));