How do I get a UTC Timestamp in JavaScript

Question

While writing a web application  it makes sense to store  server side  all datetimes in the DB as UTC timestamps   I was astonished when I noticed that you couldn t natively do much in terms of Timezone manipulation in JavaScript   I extended the Date object a little  Does this function make sense  Basically  every time I send anything to the server  it s going to be a timestamp formatted with this function     Can you see any major problems here  Or maybe a solution from a different angle   Date prototype getUTCTime   function       return new Date      this getUTCFullYear        this getUTCMonth        this getUTCDate        this getUTCHours        this getUTCMinutes         this getUTCSeconds       getTime         It just seems a little convoluted to me  And I am not so sure about performance either

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This will return the timestamp in UTC    x000D   x000D  var utc   new Date new Date   toUTCString    getTime    x000D   x000D   x000D

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Using day js In browser   x000D   x000D  dayjs extend dayjs plugin utc  console log dayjs utc   unix    x000D   lt script src  https   cdn jsdelivr net npm dayjs latest dayjs min js  gt  lt  script gt   lt script src  https   cdn jsdelivr net npm dayjs latest plugin utc js  gt  lt  script gt  x000D   x000D   x000D   In node js  import dayjs from  dayjs  dayjs extend require  dayjs plugin utc    console log dayjs utc   unix     You get a UTC unix timestamp without milliseconds

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I think this is a better solution     UTC milliseconds new Date Date now    new Date   getTimezoneOffset   60000   getTime       UTC seconds new Date Date now    new Date   getTimezoneOffset   60000   getTime   1000 0

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I actually think Date values in js are far better than say the C  DateTime objects  The C  DateTime objects have a Kind property  but no strict underlying time zone as such  and time zone conversions are difficult to track if you are converting between two non UTC and non local times  In js  all Date values have an underlying UTC value which is passed around and known regardless of the offest or time zone conversions that you do  My biggest complaint about the Date object is the amount of undefined behaviour that browser implementers have chosen to include  which can confuse people who attack dates in js with trial and error than reading the spec  Using something like iso8601 js solves this varying behaviour by defining a single implementation of the Date object   By default  the spec says you can create dates with an extended ISO 8601 date format like  var someDate   new Date  2010-12-12T12 00Z      So you can infer the exact UTC time this way    When you want to pass the Date value back to the server you would call  someDate toISOString      or if you would rather work with a millisecond timestamp  number of milliseconds from the 1st January 1970 UTC   someDate getTime      ISO 8601 is a standard  You can t be confused about what a date string means if you include the date offset  What this means for you as a developer is that you never have to deal with local time conversions yourself  The local time values exist purely for the benefit of the user  and date values by default display in their local time  All the local time manipulations allow you to display something sensible to the user and to convert strings from user input  It s good practice to convert to UTC as soon as you can  and the js Date object makes this fairly trivial   On the downside there is not a lot of scope for forcing the time zone or locale for the client  that I am aware of   which can be annoying for website-specific settings  but I guess the reasoning behind this is that it s a user configuration that shouldn t be touched   So  in short  the reason there isn t a lot of native support for time zone manipulation is because you simply don t want to be doing it

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Dates constructed that way use the local timezone  making the constructed date incorrect  To set the timezone of a certain date object is to construct it from a date string that includes the timezone   I had problems getting that to work in an older Android browser   Note that getTime   returns milliseconds  not plain seconds    For a UTC Unix timestamp  the following should suffice   Math floor  new Date    getTime     1000    It will factor the current timezone offset into the result  For a string representation  David Ellis  answer works   To clarify   new Date Y  M  D  h  m  s    That input is treated as local time  If UTC time is passed in  the results will differ  Observe  I m in GMT  02 00 right now  and it s 07 50     gt  var d1   new Date     gt  d1 toUTCString     Sun  18 Mar 2012 05 50 34 GMT     two hours less than my local time  gt  Math floor d1 getTime    1000  1332049834    gt  var d2   new Date  d1 getUTCFullYear    d1 getUTCMonth    d1 getUTCDate    d1 getUTCHours    d1 getUTCMinutes    d1 getUTCSeconds       gt  d2 toUTCString     Sun  18 Mar 2012 03 50 34 GMT     four hours less than my local time  and two hours less than the original time - because my GMT 2 input was interpreted as GMT 0   gt  Math floor d2 getTime    1000  1332042634   Also note that getUTCDate   cannot be substituted for getUTCDay    This is because getUTCDate   returns the day of the month  whereas  getUTCDay   returns the day of the week

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Once you do this  new Date dateString  getTime     1000   It is already UTC time stamp     const getUnixTimeUtc    dateString   new Date      gt  Math round new Date dateString  getTime     1000    I tested on https   www unixtimestamp com index php

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I am amazed at how complex this question has become   These are all identical  and their integer values all     EPOCH time  D  console log  new Date    getTime     1000  new Date   valueOf     1000   new Date   - new Date   getTimezoneOffset     60   1000    1000     Do not believe me  checkout  http   www epochconverter com

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I think this what you are expecting     var currTimestamp   Date now      1482905176396     utcDateString    new Date currTimestamp   toUTCString       Wed  28 Dec 2016 06 06 50 GMT    Now   new Date utcDateString  getTime      This will give you UTC Timestamp in JavaScript

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I use the following   Date prototype getUTCTime   function       return this getTime  - this getTimezoneOffset   60000         Once defined this method you can do   var utcTime   new Date   getUTCTime

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EDIT  The code below does NOT work  I was always assuming that new Date   getTime   returned the number of seconds since the 1st of January 1970 IN THE CURRENT TIMEZONE  This is not the case  getTime   returns the number of seconds in UTC  So  the code below does gross over-adjusting  Thank you everybody    First of all  thank you for your fantastic insights  I guess my question had the wrong title    it should have been  Get the UTC Unix Timestamp for an existing date    So  if I have a date object   var d   new Date 2009 01 31    I was after a function that would tell me  The UTC Unix Timestamp    This function seems to be the real trick   Date prototype getUTCUnixTime    function       return Math floor  new Date      this getUTCFullYear        this getUTCMonth        this getUTCDate        this getUTCHours        this getUTCMinutes         this getUTCSeconds       getTime     1000        Note that it works on  this   This means that I can do   var n   new Date 2008 10 10           n getUTCUnixTime      And get the number of seconds since the 1st of Jan 1970 in Unix time  Right   It s a little insane  to me  that Javascript stores everything in UTC times  but then in order to get that number I have to create a new Date object passing the individual UTC getters and then finally call getTime   for that     Merc

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You generally don t need to do much of  Timezone manipulation  on the client side  As a rule I try to store and work with UTC dates  in the form of ticks or  number of milliseconds since midnight of January 1  1970   This really simplifies storage  sorting  calculation of offsets  and most of all  rids you of the headache of the  Daylight Saving Time  adjustments  Here s a little JavaScript code that I use   To get the current UTC time   function getCurrentTimeUTC           RETURN                number of milliseconds between current UTC time and midnight of January 1  1970     var tmLoc   new Date          The offset is in minutes -- convert it to ms     return tmLoc getTime     tmLoc getTimezoneOffset     60000      Then what you d generally need is to format date time for the end-user for their local timezone and format  The following takes care of all the complexities of date and time formats on the client computer   function formatDateTimeFromTicks nTicks           nTicks    number of milliseconds since midnight of January 1  1970       RETURN                Formatted date time     return new Date nTicks  toLocaleString       function formatDateFromTicks nTicks           nTicks    number of milliseconds since midnight of January 1  1970       RETURN                Formatted date     return new Date nTicks  toLocaleDateString       function formatTimeFromTicks nTicks           nTicks    number of milliseconds since midnight of January 1  1970       RETURN                Formatted time     return new Date nTicks  toLocaleTimeString        So the following example   var ticks   getCurrentTimeUTC       Or get it from the server  var   s    ticks     ticks           DateTime     formatDateTimeFromTicks ticks           Date     formatDateFromTicks ticks           Time     formatTimeFromTicks ticks    document write   lt span gt       s     lt  span gt       Returns the following  for my U S  English locale       ticks 1409103400661  DateTime 8 26 2014 6 36 40 PM  Date 8 26 2014    Time 6 36 40 PM

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If you want a one liner  The UTC Unix Timestamp can be created in JavaScript as  var currentUnixTimestap       new Date     1000    This will take in account the timezone of the system  It is basically time elapsed in Seconds since epoch  How it works   Create date object   new Date    Convert to timestamp by adding unary   before object creation to convert it to timestamp integer     new Date    Convert milliseconds to seconds   new Date     1000 Use double tildes to round off the value to integer        new Date

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I want to make clear that new Date   getTime   does in fact return a UTC value  so it is a really helpful way to store and manage dates in a way that is agnostic to localized times   In other words  don t bother with all the UTC javascript functions  Instead  just use Date getTime     More info on the explanation is here  If javascript  quot  new Date    getTime   quot  is run from 2 different Timezones

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The easiest way of getting UTC time in a conventional format is as follows   new Date   toISOString    2016-06-03T23 15 33 008Z

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You could also do it utilizing getTimezoneOffset and getTime    x000D   x000D  x   new Date   x000D  var UTCseconds    x getTime     x getTimezoneOffset   60 1000  1000  x000D   x000D  console log  UTCseconds   UTCseconds  x000D   x000D   x000D

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Since new Date   toUTCString  returns a string like  Wed  11 Oct 2017 09 24 41 GMT  you can slice the last 3 characters and pass the sliced string to new Date     new Date      Wed Oct 11 2017 11 34 33 GMT 0200  CEST   new Date new Date   toUTCString   slice 0  -3      Wed Oct 11 2017 09 34 33 GMT 0200  CEST

[javascript] How do I get a UTC Timestamp in JavaScript?

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