如何忽略用户的时区并强制 Date() 使用特定时区 [英] How to ignore user's time zone and force Date() use specific time zone

问题描述

在一个 JS 应用程序中，我从服务器 (Ajax) 收到时间戳(例如 1270544790922).

In an JS app, I receive timestamp (eq. 1270544790922) from server (Ajax).

基于该时间戳，我使用以下方法创建 Date 对象:

Basing on that timestamp I create Date object using:

var _date = new Date();
_date.setTime(1270544790922);

现在，_date 解码当前用户区域设置时区的时间戳.我不想那样.

Now, _date decoded timestamp in current user locale time zone. I don't want that.

我希望 _date 将此时间戳转换为欧洲赫尔辛基市的当前时间(不考虑用户的当前时区).

I would like _date to convert this timestamp to current time in city of Helsinki in Europe (disregarding current time zone of the user).

我该怎么做?

推荐答案

Date 对象的基础值实际上是 UTC.为了证明这一点，请注意，如果您键入 new Date(0)，您将看到类似以下内容:Wed Dec 31 1969 16:00:00 GMT-0800 (PST).0 在 GMT 中被视为 0，但 .toString() 方法显示的是当地时间.

A Date object's underlying value is actually in UTC. To prove this, notice that if you type new Date(0) you'll see something like: Wed Dec 31 1969 16:00:00 GMT-0800 (PST). 0 is treated as 0 in GMT, but .toString() method shows the local time.

重要提示，UTC 代表通用时间码.现在两个不同地方的当前时间是相同的 UTC，但输出的格式可以不同.

Big note, UTC stands for Universal time code. The current time right now in 2 different places is the same UTC, but the output can be formatted differently.

这里我们需要的是一些格式

var _date = new Date(1270544790922); 
// outputs > "Tue Apr 06 2010 02:06:30 GMT-0700 (PDT)", for me
_date.toLocaleString('fi-FI', { timeZone: 'Europe/Helsinki' });
// outputs > "6.4.2010 klo 12.06.30"
_date.toLocaleString('en-US', { timeZone: 'Europe/Helsinki' });
// outputs > "4/6/2010, 12:06:30 PM"

这有效，但是....您不能真正使用任何其他日期方法来达到您的目的，因为它们描述了用户的时区.您想要的是与赫尔辛基时区相关的日期对象.此时您的选择是使用一些 3rd 方库(我推荐这个)，或者修改日期对象以便您可以使用它的大部分方法.

This works but.... you can't really use any of the other date methods for your purposes since they describe the user's timezone. What you want is a date object that's related to the Helsinki timezone. Your options at this point are to use some 3rd party library (I recommend this), or hack-up the date object so you can use most of it's methods.

选项 1 - 像moment-timezone这样的第三者

moment(1270544790922).tz('Europe/Helsinki').format('YYYY-MM-DD HH:mm:ss')
// outputs > 2010-04-06 12:06:30
moment(1270544790922).tz('Europe/Helsinki').hour()
// outputs > 12

这看起来比我们接下来要做的要优雅得多.

This looks a lot more elegant than what we're about to do next.

选项 2 - 修改日期对象

var currentHelsinkiHoursOffset = 2; // sometimes it is 3
var date = new Date(1270544790922);
var helsenkiOffset = currentHelsinkiHoursOffset*60*60000;
var userOffset = _date.getTimezoneOffset()*60000; // [min*60000 = ms]
var helsenkiTime = new Date(date.getTime()+ helsenkiOffset + userOffset);
// Outputs > Tue Apr 06 2010 12:06:30 GMT-0700 (PDT)

它仍然认为它是 GMT-0700 (PDT)，但如果您不仔细看，您可能会将其误认为是对您的目的有用的日期对象.

It still thinks it's GMT-0700 (PDT), but if you don't stare too hard you may be able to mistake that for a date object that's useful for your purposes.

我很方便地跳过了一部分.您需要能够定义 currentHelsinkiOffset.如果您可以在服务器端使用 date.getTimezoneOffset() ，或者仅使用一些 if 语句来描述时区更改的时间，那应该可以解决您的问题.

I conveniently skipped a part. You need to be able to define currentHelsinkiOffset. If you can use date.getTimezoneOffset() on the server side, or just use some if statements to describe when the time zone changes will occur, that should solve your problem.

结论 - 我认为特别是为了这个目的，你应该使用像 moment-timezone 这样的日期库.

Conclusion - I think especially for this purpose you should use a date library like moment-timezone.

这篇关于如何忽略用户的时区并强制 Date() 使用特定时区的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！