如何在浏览器和服务器之间保留 JavaScript 日期的时区？
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How do you preserve a JavaScript date's time zone from browser to server, and back?
提问by brushleaf
For example, using a date and time control, the user selects a date and time, such that the string representation is the following:
例如，使用日期和时间控件，用户选择日期和时间，这样字符串表示如下：
"6-25-2012 12:00:00 PM"
It so happens that this user is in the EST time zone. The string is passed to the server, which translates it into a .NET DateTime object, and then stores it in SQL Server in a datetime column.
碰巧此用户位于 EST 时区。该字符串被传递到服务器，服务器将其转换为 .NET DateTime 对象，然后将其存储在 SQL Server 中的日期时间列中。
When the date is returned later to the browser, it needs to be converted back into a date, however when the above string is fed into a date it is losing 4 hours of time. I believe this is because when not specifying a timezone while creating a JavaScript date, it defaults to local time, and since EST is -400 from GMT, it subtracts 4 hours from 12pm, even though that 12pm was meant to be specified as EST when the user selected it on a machine in the EST time zone.
当日期稍后返回到浏览器时，需要将其转换回日期，但是当将上述字符串输入日期时，它会损失 4 小时的时间。我相信这是因为在创建 JavaScript 日期时未指定时区时，它默认为当地时间，并且由于 EST 是格林威治标准时间的 -400，因此它从下午 12 点减去 4 小时，即使下午 12 点被指定为美国东部时间用户在 EST 时区的机器上选择了它。
Clearly something needs to be added to the original datetime string before its passed to the server to be persisted. What is the recommended way of doing this?
很明显，需要在原始日期时间字符串中添加一些内容，然后才能将其传递给服务器以进行持久化。这样做的推荐方法是什么？
回答by Matt Johnson-Pint
Don't rely on JavaScript's Dateconstructor to parse a string. The behavior and supported formats vary wildly per browser and locale. Hereare just someof the default behaviors if you use the Dateobject directly.
不要依赖 JavaScript 的Date构造函数来解析字符串。行为和支持的格式因浏览器和语言环境而异。 如果您直接使用对象，这里只是一些默认行为Date。
If you must come from a string, try using a standardized format such as ISO8601. The date you gave in that format would be "2012-06-25T12:00:00". The easiest way to work with these in JavaScript is with moment.js.
如果必须来自字符串，请尝试使用标准化格式，例如 ISO8601。您以该格式提供的日期将是"2012-06-25T12:00:00". 在 JavaScript 中使用这些最简单的方法是使用moment.js。
Also, be careful about what you are actually meaning to represent. Right now, you are passing a local date/time, saving a local/date/time, and returning a local date/time. Along the way, the idea of what is "local" could change.
另外，请注意您实际要代表的内容。现在，您正在传递本地日期/时间，保存本地/日期/时间，并返回本地日期/时间。一路上，什么是“本地”的想法可能会改变。
In many cases, the date/time is intended to represent an exactmoment in time. To make that work, you need to convert from the local time entered to UTC on the client. Send UTC to your server, and store it. Later, retrieve UTC and send it back to your client, process it as UTC and convert back to local time. You can do all of this easily with moment.js:
在许多情况下，日期/时间旨在代表一个确切的时刻。要使该工作正常进行，您需要将输入的本地时间转换为客户端上的 UTC。将 UTC 发送到您的服务器，并存储它。稍后，检索 UTC 并将其发送回您的客户端，将其作为 UTC 处理并转换回本地时间。您可以使用 moment.js 轻松完成所有这些：
// I'll assume these are the inputs you have. Adjust accordingly.
var dateString = "6-25-2012";
var timeString = "12:00:00 PM";
// Construct a moment in the default local time zone, using a specific format.
var m = moment(dateString + " " + timeString, "M-D-YYYY h:mm:ss A");
// Get the value in UTC as an ISO8601 formatted string
var utc = m.toISOString(); // output: "2012-06-25T19:00:00.000Z"
On the server in .Net:
在 .Net 的服务器上：
var dt = DateTime.Parse("2012-06-25T19:00:00.000Z", // from the input variable
CultureInfo.InvariantCulture, // recommended for ISO
DateTimeStyles.RoundtripKind) // honor the Z for UTC kind
Store that in the database. Later retrieve it and send it back:
将其存储在数据库中。稍后检索它并将其发回：
// when you pull it from your database, set it to UTC kind
var dt = DateTime.SpecifyKind((DateTime)reader["yourfield"], DateTimeKind.Utc);
// send it back in ISO format:
var s = dt.ToString("o"); // "o" is the ISO8601 "round-trip" pattern.
Pass it back to the javascript in moment.js:
将其传递回 moment.js 中的 javascript：
// construct a moment:
var m = moment("2012-06-25T19:00:00.000Z"); // use the value from the server
// display it in this user's local time zone, in whatever format you want
var s = m.format("LLL"); // "June 25 2012 12:00 PM"
// or if you need a Date object
var dt = m.toDate();
See - that was easy, and you didn't need to get into anything fancy with time zones.
看 - 这很容易，而且您不需要对时区进行任何花哨的处理。
回答by DimeZilla
Here, I think this is what you are looking for: How to ignore user's time zone and force Date() use specific time zone
在这里，我认为这就是您要查找的内容： How to ignore user's time zone and force Date() use specific time zone
It seems to me that you can do something like this:
在我看来，你可以做这样的事情：
var date = new Date("6-25-2012 12:00:00 PM");
var offset = date.getTimezoneOffset(); // returns offset from GMT in minutes
// to convert the minutes to milliseconds
offset *= 60000;
// the js primitive value is unix time in milliseconds so this retrieves the
// unix time in milliseconds and adds our offset.
// Now we can put this all back in a date object
date = new Date(date.valueOf() + offset);
// to get back your sting you can maybe now do something like this:
var dateString = date.toLocaleString().replace(/\//g,'-').replace(',','');
回答by Hasse
I am using a filter before sending the date to the server vm.dateFormat = 'yyyy-MM-dd'; dateToSendToServer = $filter('date')(dateFromTheJavaScript, vm.dateFormat);
我在将日期发送到服务器之前使用过滤器 vm.dateFormat = 'yyyy-MM-dd'; dateToSendToServer = $filter('date')(dateFromTheJavaScript, vm.dateFormat);
回答by Please_Dont_Bully_Me_SO_Lords
Blame the JSON.Stringfy()... and do:
归咎于 JSON.Stringfy()... 并执行以下操作：
x = (your_date);
x.setHours(x.getHours() - x.getTimezoneOffset() / 60);
