How do you convert a JavaScript date to UTC

Question

Suppose a user of your website enters a date range   2009-1-1 to 2009-1-3   You need to send this date to a server for some processing  but the server expects all dates and times to be in UTC    Now suppose the user is in Alaska or Hawaii or Fiji  Since they are in a timezone quite different from UTC  the date range needs to be converted to something like this   2009-1-1T8 00 00 to 2009-1-4T7 59 59   Using the JavaScript Date object  how would you convert the first  localized  date range into something the server will understand

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Date prototype toUTCArray  function        var D  this      return  D getUTCFullYear    D getUTCMonth    D getUTCDate    D getUTCHours        D getUTCMinutes    D getUTCSeconds        Date prototype toISO  function        var tem  A  this toUTCArray    i  0      A 1    1      while i   lt 7           tem  A i           if tem lt 10  A i    0  tem            return A splice 0  3  join  -    T  A join

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The toISOString   method returns a string in simplified extended ISO format  ISO 8601   which is always 24 or 27 characters long  YYYY-MM-DDTHH mm ss sssZ or   YYYYYY-MM-DDTHH mm ss sssZ  respectively   The timezone is always zero UTC offset  as denoted by the suffix  quot Z quot    Source   MDN web docs The format you need is created with the  toISOString   method  For older browsers  ie8 and under   which don t natively support this method  the shim can be found here  This will give you the ability to do what you need   x000D   x000D  var isoDateString   new Date   toISOString    console log isoDateString   x000D   x000D   x000D   For Timezone work  moment js and moment js timezone are really invaluable tools   especially for navigating timezones between client and server javascript

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Convert to ISO without changing date time  var now   new Date       Fri Feb 20 2015 19 29 31 GMT 0530  India Standard Time   var isoDate   new Date now getTime   - now getTimezoneOffset     60000  toISOString      OUTPUT   2015-02-20T19 29 31 238Z   Convert to ISO with change in date time date time will be changed   isoDate   new Date now  toISOString      OUTPUT   2015-02-20T13 59 31 238Z    Fiddle link

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var myDate   new Date       Set this to your date in whichever timezone  var utcDate   myDate toUTCString

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So this is the way I had to do it because i still wanted a JavaScript date object to manipulate as a date and unfortunantly alot of these answers require you to go to a string      First i had a string called stringDateVar that i needed to convert to Date var newDate   new Date stringDateVar     output  2019-01-07T04 00 00 000Z   I needed it 2019-01-07T00 00 00 000Z because i had other logic that was dependent on that   var correctDate   new Date newDate setUTCHours 0      This will output 2019-01-07T00 00 00 000Z on everything which allows scalability

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This method will give you   2017-08-04T11 15 00 000 04 30 and you can ignore zone variable to simply get 2017-08-04T11 15 00 000   function getLocalIsoDateTime dtString        if dtString                return         var offset   new Date   getTimezoneOffset        var localISOTime    new Date new Date dtString  - offset   60000   offset in milliseconds     toISOString   slice 0 -1         Next two lines can be removed if zone isn t needed      var absO   Math abs offset       var zone    offset  lt  0          -       00    Math floor absO   60   slice -2            00     absO   60   slice -2       return localISOTime   zone

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Browsers may differ  and you should also remember to not trust any info generated by the client  that being said  the below statement works for me  Google Chrome v24 on Mac OS X 10 8 2   var utcDate   new Date new Date   getTime        edit   How is this different than just new Date     see here  https   developer mozilla org en-US docs Web JavaScript Reference Global Objects Date   If no arguments are provided  the constructor creates a JavaScript Date object for the current date and time according to system settings  Note  Where Date is called as a constructor with more than one argument  the specifed arguments represent local time  If UTC is desired  use new Date Date UTC       with the same arguments   note  Date UTC   returns the number of millisecond since 1970-01-01 00 00 00 UTC      Adding the 60000   Date getTimezoneOffset   as previous answers have stated is incorrect  First  you must think of all Dates Times as already being UTC with a timezone modifier for display purposes   Again  browsers may differ  however  Date getTime   returns the number of milliseconds since 1970-01-01 UTC GMT  If you create a new Date using this number as I do above  it will be UTC GMT   However  if you display it by calling  toString   it will appear to be in your local timezone because  toString   uses your local timezone  not the timezone of the Date object it is called on   I have also found that if you call  getTimezoneOffset   on a date  it will return your local timezone  not the timezone of the date object you called it on  I can t verify this to be standard however    In my browser  adding 60000   Date getTimezoneOffset   creates a DateTime that is not UTC  However when displayed within my browser  ex   toString      it displays a DateTime in my local timezone that would be correct UTC time if timezone info is ignored

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Another solution to convert to UTC and keep it as a date object   It works by removing the   GMT  part from the end of the formatted string  then putting it back into the Date constructor   x000D   x000D  var now   new Date    var now utc   new Date now toUTCString   slice 0  -4    console log now utc  x000D   x000D   x000D   I needed to do this to interface with a datetime picker library  But in general it s a bad idea to work with dates this way  Users generally want to work with datetimes in their local time  so you either update the server side code to parse datetime strings with offsets correctly  then convert to UTC  best option  or you convert to a UTC string client-side before sending to the server  like in Will Stern s answer

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Simple and stupid   var date   new Date     var now utc    Date UTC date getUTCFullYear    date getUTCMonth    date getUTCDate     date getUTCHours    date getUTCMinutes    date getUTCSeconds       return new Date now utc

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Using moment package  you can easily convert a date string of UTC to a new Date object   const moment   require  moment    let b   new Date moment utc  2014-02-20 00 00 00 000000     let utc   b toUTCString    b getTime      This specially helps when your server do not support timezone and you want to store UTC date always in server and get it back as a new Date object  Above code worked for my requirement of similar issue that this thread is for  Sharing here so that it can help others  I do not see exactly above solution in any answer  Thanks

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Using moment js UTC method   const moment   require  moment    const utc   moment utc new Date string

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I know this question is old  but was looking at this same issue  and one option would be to send date valueOf   to the server instead  the valueOf   function of the javascript Date sends the number of milliseconds since midnight January 1  1970 UTC   valueOf

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If you are dealing with dates a lot  it s worth using moment js  http   momentjs com   The method to convert to UTC would be   moment yourTime  utc     You can use format to change your date to any format you want   moment yourTime  utc   format  YYYY-MM-DD     There is offset options in moment as well but there is an additional complementary library for dealing with timezone  http   momentjs com timezone    The time conversion would be as simple as this   moment tz yourUTCTime   America New York

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date    2012-07-28   stringdate   new Date date  toISOString      ought to work in most newer browsers  it returns 2012-07-28T00 00 00 000Z on Firefox 6 0

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var userdate   new Date  2009-1-1T8 00 00Z    var timezone   userdate getTimezoneOffset    var serverdate   new Date userdate setMinutes userdate getMinutes   parseInt timezone       This will give you the proper UTC Date and Time  It s because the getTimezoneOffset   will give you the timezone difference in minutes  I recommend you that not to use toISOString   because the output will be in the string Hence in future you will not able to manipulate the date

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If you need Date Object  Passing only date string Date assumes time to be 00 00 shifted by time zone   new Date  2019-03-11   Sun Mar 10 2019 18 00 00 GMT-0600  Central Standard Time    If you add current hours and minutes you get proper date   new Date  2019-03-11     new Date   getHours           new Date   getMinutes    Mon Mar 11 2019 04 36 00 GMT-0600  Central Standard Time

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My solution keeps the date the same no matter what timezone is set on the client-side  Maybe someone will find it useful   My use case   I m creating a todo app  where you set date of your task  This date should remain constant no matter what timezone you re in   Example  You want to call your friend at 8 am on June 25th   You create this task 5 days before  June 20th  while you re in China    Then  on the same day  you fly to New York for a few days   Then on June 25th  while you re still in New York  you wake up at 7 30 am  which means you should receive task notification in 30 mins  even tho it s 1 30 pm already in China where you were when creating the task   So the task is ignoring the timezone  It means  I want to do it at 8 am in whatever timezone I ll be in    What I do is let s say  I assume you re always in London Timezone - UTC    What it means is - when the user picks some date in her his Timezone - I convert this date to the same date in UTC  ie  You pick 8 am in China  but I convert it to 8 am in UTC   Then - next time you open the app - I read the date saved in UTC and convert it to the same date in your current timezone - eg  I convert 8 am in UTC to 8 am in the New York timezone   This solution means that the date can mean something else depending on where you are when setting it and where you re reading it  but it remains constant in a way that it  feels  like you re always in the same timezone   Let s write some code   First - we have 2 main functions for converting from to UTC ignoring timezone   export function convertLocalDateToUTCIgnoringTimezone date  Date      const timestamp   Date UTC      date getFullYear        date getMonth        date getDate        date getHours        date getMinutes        date getSeconds        date getMilliseconds            return new Date timestamp      export function convertUTCToLocalDateIgnoringTimezone utcDate  Date      return new Date      utcDate getUTCFullYear        utcDate getUTCMonth        utcDate getUTCDate        utcDate getUTCHours        utcDate getUTCMinutes        utcDate getUTCSeconds        utcDate getUTCMilliseconds             Then  I save read this date like   function saveTaskDate localDate  Date         I convert your local calendar date so it looks like you ve picked it being in UTC somewhere around London   const utcDate   convertLocalDateToUTCIgnoringTimezone localDate     api saveTaskDate utcDate      function readTaskDate taskUtcDate  Date         I convert this UTC date to  look in your local timezone  as if you were now in UTC somewhere around london   const localDateWithSameDayAsUTC   convertUTCToLocalDateIgnoringTimezone taskUtcDate         this date will have the same calendar day as the one you ve picked previously      no matter where you were saving it and where you are now

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Even simpler  myvar setTime myvar getTime     myvar getTimezoneOffset     60000

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I ve found the jQuery Globalization Plugin date parsing to work best   Other methods had cross-browser issues and stuff like date js had not been updated in quite a while    You also don t need a datePicker on the page   You can just call something similar to the example given in the docs     parseDate  yy-mm-dd    2007-01-26

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This is what I have done in the past   var utcDateString   new Date new Date   toUTCString    toISOString

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const event   new Date     console log event toUTCString

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The getTimezoneOffset   method returns the time zone difference  in minutes  from current locale  host system settings  to UTC   Source  MDN web docs This means that the offset is positive if the local timezone is behind UTC  and negative if it is ahead  For example  for time zone UTC 02 00  -120 will be returned   x000D   x000D  let d   new Date    console log d   d setTime d getTime      d getTimezoneOffset     60000    console log d   x000D   x000D   x000D   NOTE  This will shift the date object time to UTC  00 00 and not convert its timezone so the date object timezone will still the same but the value will be in UTC  00 00

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I just discovered that the 1 2 3 version of Steven Levithan s date format js does just what I want  It allows you to supply a format string for a JavaScript date and will convert from local time to UTC  Here s the code I m using now      JavaScript dates don t like hyphens      var rectifiedDateText   dateText replace  - g        var d   new Date rectifiedDateText       Using a predefined mask from date format js  var convertedDate   dateFormat d   isoUtcDateTime

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Looking at your question its clear that you just want to send the date range to your backend for further post processing   I am assuming you are conforming to the standard data guidelines which expect the data to be in a particular format  For example  I use ODATA which is a RESTfull API which expects date time objects to be in the format -     YYYY-MM-DDT00 00 00    That can be easily achieved via the snippet posted below Please change the format as per your requirement     var mydate   assuming this is my date object which I want to expose var UTCDateStr   mydate getUTCFullYear      -    mydate getUTCMonth      -    mydate getUTCDate      T00 00 00    If on the other hand  you are in my situation wherein you have received a date from your backend  and the browser converts that to your local date  You on the other hand are interested in the UTC date then you can perform the following -  var mydate   assuming this is my date object which I want to expose var UTCDate   new Date mydate    create a copy of your date object  Only needed if you for some reason need the original local date   UTCDate setTime UTCDate getTime     UTCDate getTimezoneOffset     60   1000    The code snippet above basically adds subtracts the time added subtracted by the browser based on the timezone    For example if I am in EST GMT-5  and my Service returns a date time object   Wed Aug 17 2016 00 00 00 GMT-0500 my browser automatically subtracts the timezone offset 5hrs  to get my local time  So if I try to fetch the time I get Wed Aug 16 2016 19 00 00 GMT-0500  This causes a lot of problems  There are a lot of libraries out there which will definitely make this easier but I wanted to share the pure JS approach    For more info please have a look at  http   praveenlobo com blog how-to-convert-javascript-local-date-to-utc-and-utc-to-local-date  where in I got my inspiration   Hope this helps

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Are you trying to convert the date into a string like that   I d make a function to do that  and  though it s slightly controversial  add it to the Date prototype  If you re not comfortable with doing that  then you can put it as a standalone function  passing the date as a parameter   Date prototype getISOString   function         var zone       temp   -this getTimezoneOffset     60   100      if  temp  gt   0  zone             zone     Math abs temp   lt  100    00     Math abs temp   lt  1000    0           temp           2009-6-4T14 7 32 10 00      return this getFullYear        2009             -              this getMonth     1     6             -             this getDate            4             T             this getHours           14                           this getMinutes         7                           this getSeconds         32            zone substr 0  3         10                           String temp  substr -2     00            If you needed it in UTC time  just replace all the get  functions with getUTC   eg  getUTCFullYear  getUTCMonth  getUTCHours    and then just add   00 00  at the end instead of the user s timezone offset

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My recommendation when working with dates is to parse the date into individual fields from user input  You can use it as a full string  but you are playing with fire   JavaScript can treat two equal dates in different formats differently   https   developer mozilla org en-US docs Web JavaScript Reference Global Objects Date parse  Never do anything like   new Date  date as text      Once you have your date parsed into its individual fields from user input  create a date object  Once the date object is created convert it to UTC by adding the time zone offset  I can t stress how important it is to use the offset from the date object due to DST  that s another discussion however to show why    var year   getFullYear  date as text    var month   getMonth  date as text    var dayOfMonth   getDate  date as text     var date   new Date year  month  dayOfMonth    var offsetInMs     date getTimezoneOffset     60      Seconds                    1000                                Milliseconds  var utcDate   new Date date getTime   offsetInMs     Now you can pass the date to the server in UTC time  Again I would highly recommend against using any date strings  Either pass it to the server broken down to the lowest granularity you need e g  year  month  day  minute or as a value like milliseconds from the unix epoch

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This function works beautifully for me   function ParseDateForSave dateValue           create a new date object     var newDate   new Date parseInt dateValue substr 6             return the UTC version of the date     return newDate toISOString

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You can use the following method to convert any js date to UTC   let date   new Date YOUR DATE  toISOString       It would give the date in format  2020-06-16T12 30 00 000Z  where Part before T is date in YYYY-MM-DD format  part after T is time in format HH MM SS  and Z stands for UTC - Zero hour offset

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Here s my method   var now   new Date    var utc   new Date now getTime     now getTimezoneOffset     60000     The resulting utc object isn t really a UTC date  but a local date shifted to match the UTC time  see comments   However  in practice it does the job

[javascript] How do you convert a JavaScript date to UTC?

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