如何使用moment.js和moment-timezone.js将特定时区（非本地）的给定日期/时间转换为UTC

Question

How can II want to convert a given date/time for a specific timezone (not local) to UTC using moment.js and moment-timezone.js
I use:

var s = moment("10/15/2014 09:25 AM").tz("America/Los_Angeles").format('hh:mm:ss a'); 

I have a difficulty when I want to give a value on moment() .
Let me explain you the facts:
I have to take a date/time value from a cell with the following format: 10/15/2014 09:25 AM (MM/DD/YYYY h:mm a) . This value is not a constant one, its the opened time for some entries. I want to transform this string in UTC. Unfortunately, the string is not my local time, is in America/Los_Angeles (PDT/PST) timezone. I want also to take care automatically about PDT(9 Mar, 2 Nov) and PST .

-10/15/2014 09:25 AM America/Los_Angeles -07:00 => 10/15/2014 04:25 PM UTC 00:00
-12/15/2014 09:25 AM America/Los_Angeles -08:00 => 12/15/2014 05:25 PM UTC 00:00    

How can I do this?

If I use:
Var s = moment("10/15/2014 09:37 PM").tz("America/Los_Angeles").format('hh:mm:ss a'); ...it will be parsed as my local time and it will be converted to America/Los_Angeles .

- 10/15/2014 09:25 AM Eastern European Time +03:00 => 10/15/2014 11:25 PM America/Los_Angeles +07:00

I think that a short description for my problem is this:
- How can I "tell" to script that this string 10/15/2014 09:37 AM is from a specific timezone. After this, the conversion to UTC is piece of cake.

Thanks.

Answer 1

You must provide a pattern when you want to parse a date string with a specific timezone, except for UTC. For UTC you can just provide the date string.

Usage: moment.tz(string, pattern, zoneString)

In your case:

var moment = require("moment-timezone");
var d1 = moment.tz("10/15/2014 09:25 AM", "MM/DD//YYYY hh:mm A", "America/Los_Angeles");
d1.toString(); // Wed Oct 15 2014 09:25:00 GMT-0700
d1.tz("UTC").format('hh:mm:ss a'); // '04:25:00 pm'

If you omit the formatter the parsing is wrong, but there is a deprecated note: https://github.com/moment/moment/issues/1407

Read this http://momentjs.com/timezone/docs/#/using-timezones/parsing-ambiguous-inputs/ to handle DST