如何使用“时间”用于在不同日历日期之间转换的 API

Question

使用 Temporal.Calendar https://github.com/tc39/proposal-temporal" rel="nofollow noreferrer">Temporal 全局对象，以下短函数在日历日期之间进行转换（在中识别的 18 个日历） JavaScript）。

目前，Temporal.Calendar 对于其他日历返回的输出日期的格式为（示例）：'2022-02-25[u-ca=persian]'

如何避免使用< code>toString().split("[")[0]) 获取不带后缀 [u-ca=CalendarName] 的日历日期Intl.DateTimeFormat() 无法识别后缀？

<script type='module'>
// ====== load Temporary polyfill (not needed after full Temporal implementation) ========
import * as TemporalModule from 'https://cdn.jsdelivr.net/npm/@js-temporal/[email protected]/dist/index.umd.js'
//=====================================================================

// Y,M,D are the date to convert from
// options as in Intl.DateTimeFormat() with additional 'from' and 'locale'
// 'from': calendar name to convert from
// 'locale' the locale to use (default 'en')
// 'calendar': calendar to convert to
// All other options as in Intl.DateTimeFormat()
//---------------------------------------
function dateToCalendars(Y, M, D, op={}) {
return new Intl.DateTimeFormat(op.locale??="en",op).format(new Date(temporal.Temporal.PlainDateTime.from({year:Y,month:M,day:D,calendar:op.from??= "gregory"}).toString().split("[")[0]));
}
//---------------------------------------

//===============================
// Example Test Cases
//===============================

console.log(dateToCalendars(2022,2,25));     // default Gregory

// full format Gregory
console.log(dateToCalendars(2022,2,25, {dateStyle: "full"}));    

// from Persian to Gregory in full format
console.log(dateToCalendars(1400,12,6,{from: 'persian', dateStyle: "full"})); 

// from Persian to Gregory in full format in 'fa' locale
console.log(dateToCalendars(1400,12,6,{from: 'persian', dateStyle: "full", locale: "fa"}));

// from Persian to Islamic in full format in 'fa' locale
console.log(dateToCalendars(1400,12,6,{from: 'persian', calendar: 'islamic', dateStyle:"full", locale: "fa"})); 

// from Islamic to Gregory full format (default 'en' locale)
console.log(dateToCalendars(1443,7,24,{from:"islamic", dateStyle:"full"}));  

// from Hebrew to Islamic in full format
console.log(dateToCalendars(5782,6,24,{from: 'hebrew', calendar:"islamic", dateStyle:"full"}));  

// from Hebrew to Islamic in full format in 'ar' locale
console.log(dateToCalendars(5782,6,24,{from: 'hebrew', calendar:"islamic", dateStyle:"full", locale: 'ar'}));  

// from Hebrew to Persian in full format
console.log(dateToCalendars(5782,6,24,{from: 'hebrew', calendar:"persian", dateStyle:"full"}));  

// from Hebrew to Gregory in full format in 'he' locale
console.log(dateToCalendars(5782,6,24,{from: 'hebrew', dateStyle:"full", locale: 'he'})); 

</script> 

Answer 1

您可以将 Temporal.PlainDateTime 对象直接传递给 Intl.DateTimeFormat，或使用 Temporal.Calendar.prototype.toLocaleString() 间接传递。这将使您不必分割字符串以删除括号。

（一个好的经验法则是，如果您发现自己使用任何 Temporal 对象的 toString() 的输出进行字符串操作，或者使用 new Date() ，这可能表明存在您应该使用一种临时方法。）

需要注意的是，您必须确保区域设置的日历与您正在格式化的日期的日历相匹配。您不能使用 toLocaleString() 或 Intl.DateTimeFormat 进行日历转换（除非它来自 ISO 8601 日历）。
因此，您应该使用 withCalendar() 方法将日期转换为您想要输出的日历，并确保 Intl 选项中的日历与其匹配。

这是我对这样一个函数的尝试：

function dateToCalendars(year, month, day, op = {}) {
  const fromCalendar = op.from ?? 'gregory';
  const toCalendar = op.calendar ?? fromCalendar;
  const date = Temporal.PlainDate.from({ year, month, day, calendar: fromCalendar })
    .withCalendar(toCalendar);
  return date.toLocaleString(op.locale ?? 'en', { ...op, calendar: toCalendar });
}