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moment-timezones.js, how to convert date in spesific timezone to utc, disregarding my local timezone?

my system uses timezone UTC+03:00 ,
im trying to get a date in string format, represented by NY timezone,
and convert it to a Date object in utc
const dateInNY = moment.tz(xlsxDate, "M/D/YYYY h:mm a", "America/New_York")
.tz("Z").toDate();
doesnt work correctly
how am i even suppose to convert to utc time?
-----------edit---------------
i got it to work, using the timezone "Africa/Accra" , where UTC offset is 0, and ther is no daylight savings time:
moment.tz(xlsxDate, "M/D/YYYY h:mm a", "America/New_York").tz("Africa/Accra")
but this solution is a bad workaround, and if the government of Accra decide to change the time laws, will stop working!
is there a way to set the utc offset to 0 in momentjs-timezones?

As Álvaro González mentioned, that Date object does not contain Time zone information.
I do the following:
new Date(moment.tz(date, currentTimezone).tz(newTimezone).format('YYYY/MM/DD HH:mm:ss'))
where date is a date object or a string (e.g. '2017-10-30 16:30:00.0000')
so, I change date from currentTimezone to newTimezone and after that new Date object will be returned
Let's change '2017-10-30 16:30:00.0000' from UTC to America/Toronto (UTC-4)
new Date(moment.tz(date, 'UTC').tz('America/Toronto').format('YYYY/MM/DD HH:mm:ss'))
And I got
Mon Oct 30 2017 12:30:00 GMT+0400
GMT+0400 is my timezone and console.log() just shows it with any
date object and it can mislead you. Please, don't look at the this
timezone.
Let's change '2017-10-30 16:30:00.0000' from Europe/Samara (UTC+4) to America/Toronto (UTC-4)
new Date(moment.tz('2017-10-30 16:30:00.0000', 'Europe/Samara').tz('America/Toronto').format('YYYY/MM/DD HH:mm:ss'))
Firstly, moment.tz undertands that date has no timezone information and associate with Europe/Samara (UTC+4)
timezone. After that computes difference between new and old
timezone (it's -8 hours in this case)
And returns result
Mon Oct 30 2017 08:30:00 GMT+0400
And answer on your question
If xsltDate is a date object or string which do not contain timezone information
dateUTC = new Date(moment.tz(xlsxDate, "America/New_York").tz("UTC").format('YYYY/MM/DD HH:mm:ss'));
If xsltDate contain timezone information (e.g.'2013-06-01T00:00:00-04:00'), then no need to tell moment.tz which timezone xlsxDate has, just mention a new timezone
dateUTC = new Date(moment.tz(xlsxDate, "UTC").format('YYYY/MM/DD HH:mm:ss'));

Short answer is that you cannot.
The .toDate() method of the Moment library returns a native Date object. Such objects do not keep memory of any specific time zone (that's one of the reasons to use Moment in the first place), they just keep track of the exact time moment represented and merely pick a time zone when formatting to string, which is either UTC or the browser's time zone (not an arbitrary one).
The long answer is that you're probably getting correct results but are printing them with a method that uses the browser's time zone.

i found a function that does what i was trying to do, it belongs to the momentjs library itself: utcOffset(n) sets the offset to n.
(i also had to explicitly write the date string format correctly, thanks VincenzoC)
this is the code i was trying to write:
const dateInNY = moment.tz(xlsxDate, "M/D/YYYY h:mm a", "America/New_York");
const dateUTC = dateInNY.utcOffset(0).toDate();
however, the toDate function changes the timezone to my local timezone anyway, so .utcOffset(0) is redundat, and i can just use moment this way:
const dateInNY = moment.tz(xlsxDate, "M/D/YYYY h:mm a", "America/New_York");
const dateUTC = dateInNY.toDate();
and change the Date objects date to utc time later (in my case, the JSON.stringify stuff i use later does that for me)

JavaScript displaying correct date from dates stored as UTC on server

I have dates stored in my database in UTC format and calling
element.createdDate = new Date(element.createdDate.toString());
results in displaying the wrong date.
calling
element.createdDate = new Date(element.createdDate.toUTCString());
returns nothing. How do I go about displaying the correct time from UTC?

It appears that your json response contains a string valued which are in ISO8601 format in UTC, and then you are creating Date objects from them.
This part of your code is fine:
if (element.createdDate) element.createdDate = new Date(element.createdDate.toString());
You parse the string, and the resulting Date object is correct.
However, you don't need to use .toString() here, as the value is already a string. That is redundant.
This part of your code is the problem:
console.log("javascript date: " + new Date(element.depositDate.getUTCDate().toString()));
The getUTCDate function returns just the date of the month. Don't use that.
No matter what you do to create the Date object, ultimately you create a Date object and you're relying upon an implicit string conversion to output it. This will have different behavior in different browsers.
Consider console.log(new Date()):
In Chrome, this logs something like Fri Mar 17 2017 12:14:29 GMT-0700 (Pacific Daylight Time) on my computer. This is as if I called console.log(new Date().toString()); It is in an RFC 2822 like format (but not quite), and is represented in local time.
In Firefox, this logs something like 2017-03-17T19:14:46.535Z. This is as if I called console.log(new Date().toISOString()); It is in ISO8601 format, and is represented in UTC.
The point is, don't rely on implicit undefined behavior. If you must work with Date objects, then you should use console.log(element.createdDate.toISOString()) to see the ISO8601 representation of the UTC time.
If you're going to be doing a lot of things with dates and times, you may prefer to use a library, such as Moment.js, which can make tasks such as this more clear.

I have dates stored in my database in UTC format and calling
element.createdDate = new Date(element.createdDate.toString());
results in displaying the wrong date.
2016-10-11T00:00:00Z and Mon Oct 10 2016 20:00:00 GMT-04:00 (EDT) are exactly the same moment in time. The only difference is that one is displayed in ISO 8601 extended format with timezone offset 00:00 and the other is displayed in an RFC 2822 (like) format with timezone offset -04:00 (and assumes a locality in the EDT region).
calling
element.createdDate = new Date(element.createdDate.toUTCString());
returns nothing.
That is unusual. Typically it would return either a string or an error, but without a working example or any code to provide context it's impossible to say why.
How do I go about displaying the correct time from UTC?
You haven't specified what "correct" is. You are displaying a date and time for the same moment in time, just in a different format and time zone.

How to parse date string from database without time shift?

I am getting 2016-07-13T00:00:00.000Z string from database and converting it to MM/DD/YYYY format with moment.js like this:
result = moment('2016-07-13T00:00:00.000Z').format('MM/DD/YYYY');
which prints 07/12/2016 but I was expecting 07/13/2016.
Local Linux timezone is America/New_York. date command prints this Mon Jul 4 04:28:19 EDT 2016

The date that you have is in UTC, as signified by the z at the end.
When you use the default moment constructor, moment(), it converts the time you pass it from the specified offset (in this case UTC) to the local time of the machine. This is why your date is changing. Because this is a UTC date, to keep it exactly the same you can use moment.utc():
moment.utc('2016-07-13T00:00:00.000Z').format('MM/DD/YYYY');
"07/13/2016"
Alternately, parseZone would work as well:
moment.parseZone('2016-07-13T00:00:00.000Z').format('MM/DD/YYYY');
"07/13/2016"
For more information about all of the constructor functions in moment, see the parsing guide
or this blog post

You should use momentjs timezone : http://momentjs.com/timezone/
yourdate = moment.tz("2016-07-13T00:00:00.000Z", "America/New_York");
alert(yourdate.format('MM/DD/YYYY'));
This should give you the correct date in output.

JS get date in UTC time

I've created a date in JS like so:
var myDate = new Date('2013-01-01 00:00:00');
I assume JS reads this in as UTC time. But when I do something like myDate.getTime() the timestamp returned was something like 4AM GMT time.
Why is this? And how do I get the date as midnight in UTC time?

At least in Chrome, this works:
var myDate = new Date('2013-01-01 00:00:00 UTC');
It also works if you put GMT instead of UTC. But I don't know if this is cross-browser enough.

I live in India. Hence my timezone is the Indian Standard Time (IST) which is listed in the tz database as Asia/Kolkata. India is 5 hours 30 minutes ahead of GMT. Hence when I execute new Date("2013-01-01 00:00:00") the actual time at GMT is "2012-12-31 18:30:00".
I believe you live in America because you're in the EST timezone (GMT-04:00)? Am I right?
If you want to parse the time at GMT instead of your local timezone then do this:
new Date("2013-01-01T00:00:00+00:00");
Notice the capital T between the date and the time, and the +00:00 at the end. This is the format used to parse a given time in a specific timezone.
Given the date string "2013-01-01 00:00:00" you can convert it to the required format using the following function:
function formatDateString(string, timezone) {
return string.replace(" ", "T") + timezone;
}
Then you can create the date as follows:
new Date(formatDateString("2013-01-01 00:00:00", "+00:00"));
Another way to convert local time to GMT is as follows:
var timezone = new Date("1970-01-01 00:00:00"); // this is the start of unix time
Now that you have your own local timezone as a date object you can do:
new Date(new Date("2013-01-01 00:00:00") - timezone);
All the above methods produce the same date at GMT.

JS reads this with time zone that your computer uses.
You can try use myDate.toUTCString() for get date in UTC time.
If you want get timestamp use myDate.getTime()

Mine works simply by doing this
var datetime= new Date()
However the month is 1 low so you have to add one

How do you check whether a date is UTC in Javascript?

I've read this question:
How do you convert a JavaScript date to UTC?
and based on this I implemented this conversion in a dateTools module as follows:
[Update]
var dt, utcTime;
dt = new Date();
utcTime = new Date(Date.UTC(dt.getFullYear(),
dt.getMonth(),
dt.getDate(),
dt.getHours(),
dt.getMinutes(),
dt.getSeconds(),
dt.getMilliseconds()));
Now I'd like to write unit tests. My idea was to check whether the result is actually in UTC, but I don't know how.
All the toString, toUTCString and similar methods seem to be identical for the input (non UTC) and output (UTC) date.
Only the result of the getTime method differs.
Is there a way to check wheter a date is UTC in javascript? If not, is there a better idea to unit test this?
To give more context:
Only converting the it to a UTC string is not that helpful, because in the next step the date is sent to an Asp.net service and therefore converted to a string like:
'/Date([time])/'
with this code
var aspDate = '/Date(' + date.getTime() + ')/';

var aspDate = '/Date(' + date.getTime() + ')/';
This outputs the internal UNIX epoch value (UTC), which represents a timestamp. You can use the various toString methods to get a more verbose string representation of that timestamp:
.toString() uses the users timezone, result is something like "Fri Jan 25 2013 15:20:14 GMT+0100" (for me, at least, you might live in a different timezone)
.toUTCString() uses UTC, and the result will look like "Fri, 25 Jan 2013 14:20:15 GMT"
.toISOString() uses UTC, and formats the datestring according to ISO: "2013-01-25T14:20:20.061Z"
So how do we construct the time value that we want?
new Date() or Date.now() result in the current datetime. No matter what the user's timezone is, the timestamp is just the current moment.
new Date(year, month, …) uses the users timezone for constructing a timestamp from the single values. If you expect this to be the same across your user community, you are screwed. Even when not using time values but only dates it can lead to odd off-by-one errors.
You can use the setYear, setMonth, … and getYear, getMonth … methods to set/get single values on existing dates according to the users timezone. This is appropriate for input from/output to the user.
getTimezoneOffset() allows you to query the timezone that will be used for all these
new Date(timestring) and Date.parse cannot be trusted. If you feed them a string without explicit timezone denotation, the UA can act random. And if you want to feed a string with a proper format, you will be able to find a browser that does not accept it (old IEs, especially).
Date.UTC(year, month, …) allows you to construct a timestamp from values in the UTC timezone. This comes in handy for input/output of UTC strings.
Every get/set method has a UTC equivalent which you can also use for these things.
You can see now that your approach to get the user-timezone values and use them as if they were in UTC must be flawed. It means either dt or utcTime has the wrong value, although using the wrong output method may let it appear correct.

getTimezoneOffset
Syntax: object.getTimezoneOffset( ) This method
returns the difference in minutes between local time and Greenwich
Mean Time. This value is not a constant, as you might think, because
of the practice of using Daylight Saving Time.
i.e.
var myDate = new Date;
var myUTCDate = new Date(myDate - myDate.getTimezoneOffset() * 60000);
alert(myUTCDate);
note: 60000 is the number of milliseconds in a minute;