像在PHP中一样在JavaScript中获取一年中的一周

javascript date

2022-08-30 01:41:01

我如何获得一年中的当前周数，就像PHP一样？date('W')

它应该是ISO-8601周数的年数，从星期一开始的周数。

答案 1

你应该能够在这里得到你想要的东西：~~http://www.merlyn.demon.co.uk/js-date6.htm#YWD~~。

同一网站上一个更好的链接是：~~使用周~~。

编辑

以下是一些基于提供的链接和Dommer发布的eiller的代码。它已针对 ~~http://www.merlyn.demon.co.uk/js-date6.htm#YWD~~ 的结果进行了轻微的测试。请彻底测试，不提供任何保证。

编辑2017年

在遵守夏令时期间，日期存在问题，1月1日是星期五的年份。通过使用所有 UTC 方法修复。下面返回与 Moment 相同的结果.js。

/* For a given date, get the ISO week number
 *
 * Based on information at:
 *
 *    THIS PAGE (DOMAIN EVEN) DOESN'T EXIST ANYMORE UNFORTUNATELY
 *    http://www.merlyn.demon.co.uk/weekcalc.htm#WNR
 *
 * Algorithm is to find nearest thursday, it's year
 * is the year of the week number. Then get weeks
 * between that date and the first day of that year.
 *
 * Note that dates in one year can be weeks of previous
 * or next year, overlap is up to 3 days.
 *
 * e.g. 2014/12/29 is Monday in week  1 of 2015
 *      2012/1/1   is Sunday in week 52 of 2011
 */
function getWeekNumber(d) {
    // Copy date so don't modify original
    d = new Date(Date.UTC(d.getFullYear(), d.getMonth(), d.getDate()));
    // Set to nearest Thursday: current date + 4 - current day number
    // Make Sunday's day number 7
    d.setUTCDate(d.getUTCDate() + 4 - (d.getUTCDay()||7));
    // Get first day of year
    var yearStart = new Date(Date.UTC(d.getUTCFullYear(),0,1));
    // Calculate full weeks to nearest Thursday
    var weekNo = Math.ceil(( ( (d - yearStart) / 86400000) + 1)/7);
    // Return array of year and week number
    return [d.getUTCFullYear(), weekNo];
}

var result = getWeekNumber(new Date());
document.write('It\'s currently week ' + result[1] + ' of ' + result[0]);

创建“UTC”日期时，小时数为零。

最小化的原型版本（仅返回周数）：

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)
};

document.write('The current ISO week number is ' + new Date().getWeekNumber());

测试部分

在本节中，您可以以 YYYY-MM-DD 格式输入任何日期，并检查此代码是否提供与 Moment 相同的周号.js ISO 周号（从 2000 年到 2050 年测试了 50 年）。

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)
};

function checkWeek() {
  var s = document.getElementById('dString').value;
  var m = moment(s, 'YYYY-MM-DD');
  document.getElementById('momentWeek').value = m.format('W');
  document.getElementById('answerWeek').value = m.toDate().getWeekNumber();      
}

<script src="https://cdnjs.cloudflare.com/ajax/libs/moment.js/2.18.1/moment.min.js"></script>

Enter date  YYYY-MM-DD: <input id="dString" value="2021-02-22">
<button onclick="checkWeek(this)">Check week number</button><br>
Moment: <input id="momentWeek" readonly><br>
Answer: <input id="answerWeek" readonly>

答案 2

您还可以使用 momentjs 库：

moment().format('W')