如何在 JavaScript 中计算 ISO 周数，就像 PHP 的'date('W')”一样？

在 JavaScript 中确定周数 就像 PHP 的 date('W')

PHP 的 date('W') 函数计算周数基于 ISO-8601 标准的年份。 ISO-8601 周数从星期一开始，一直持续到星期日。本文演示了如何在 JavaScript 中实现类似的功能。

解决方案

Merlyn 的网站提供了在 JavaScript 中使用几周的全面指南：

• [与周](https://www.merlyn.org/2005/11/04/working-with-weeks/)

根据本指南，以下代码片段返回 ISO-8601 周给定日期的编号：

/* For a given date, get the ISO week number
 *
 * Based on information at:
 *
 *    https://www.merlyn.org/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());
console.log('It\'s currently week ' + result[1] + ' of ' + result[0]);

此代码依赖于 UTC 方法来避免夏令时和特定年初场景期间出现问题。输出显示当前年份和周数，类似于 PHP 的 date('W') 函数。

以上是如何在 JavaScript 中计算 ISO 周数，就像 PHP 的'date('W')”一样？的详细内容。更多信息请关注PHP中文网其他相关文章！