使用moment.js查找给定工作日（即星期一）的下一个实例 [英] Find next instance of a given weekday (ie. Monday) with moment.js

问题描述

我想知道下周一或周四的日期（如果是周一或周四，则为今天）。由于Moment.js在星期日 - 星期六的范围内工作，我必须计算当天的时间并根据以下内容计算下周一或周四：

I want to get the date of the next Monday or Thursday (or today if it is Mon or Thurs). As Moment.js works within the bounds of a Sunday - Saturday, I'm having to work out the current day and calculate the next Monday or Thursday based on that:

if (moment().format("dddd")=="Sunday") { var nextDay = moment().day(1); }
if (moment().format("dddd")=="Monday") { var nextDay = moment().day(1); }
if (moment().format("dddd")=="Tuesday") { var nextDay = moment().day(4); }
if (moment().format("dddd")=="Wednesday") { var nextDay = moment().day(4); }
if (moment().format("dddd")=="Thursday") { var nextDay = moment().day(4); }
if (moment().format("dddd")=="Friday") { var nextDay = moment(.day(8); }
if (moment().format("dddd")=="Saturday") { var nextDay = moment().day(8); }

这有效，但肯定有更好的方法！

This works, but surely there's a better way!

推荐答案

这里的诀窍不在于使用Moment去特定的从今天开始。它正在推广它，所以你可以随时使用它，无论你在哪一周。

The trick here isn't in using Moment to go to a particular day from today. It's generalizing it, so you can use it with any day, regardless of where you are in the week.

首先你需要知道你在哪里本周： moment.day（），或稍微更可预测（尽管有语言环境） moment（）。isoWeekday（）。

First you need to know where you are in the week: moment.day(), or the slightly more predictable (in spite of locale) moment().isoWeekday().

用它来知道今天是小于还是大于你想要的那天。如果它更小/相等，你可以简单地使用本周的实例星期一或星期四......

Use that to know if today's day is smaller or bigger than the day you want. If it's smaller/equal, you can simply use this week's instance of Monday or Thursday...

const dayINeed = 4; // for Thursday
const today = moment().isoWeekday();

if (today <= dayINeed) { 
  return moment().isoWeekday(dayINeed);
}

但是，如果今天比我们想要的那天更大，你想要使用下周的同一天：下周一的星期一，无论你在当周的哪个地方。简而言之，你想首先进入下周，使用 moment（）。add（1，'weeks'）。一旦你下周，你可以使用 moment（）。day（1）选择你想要的日子。

But, if today is bigger than the day we want, you want to use the same day of next week: "the monday of next week", regardless of where you are in the current week. In a nutshell, you want to first go into next week, using moment().add(1, 'weeks'). Once you're in next week, you can select the day you want, using moment().day(1).

一起：

const dayINeed = 4; // for Thursday
const today = moment().isoWeekday();

// if we haven't yet passed the day of the week that I need:
if (today <= dayINeed) { 
  // then just give me this week's instance of that day
  return moment().isoWeekday(dayINeed);
} else {
  // otherwise, give me *next week's* instance of that same day
  return moment().add(1, 'weeks').isoWeekday(dayINeed);
}

参见https://stackoverflow.com/a/27305748/800457

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