How to ISO 8601 format a Date with Timezone Offset in JavaScript

Question

Goal  Find the local time and UTC time offset then construct the URL in following format   Example URL   Actions Sleep duration 2002-10-10T12 00 00-05 00  The format is based on the W3C recommendation  http   www w3 org TR xmlschema11-2  dateTime  The documentation says      For example  2002-10-10T12 00 00-05 00  noon on 10 October 2002         Central Daylight Savings Time as well as Eastern Standard Time in the U S          is equal to 2002-10-10T17 00 00Z  five hours later than 2002-10-10T12 00 00Z    So based on my understanding  I need to find my local time by new Date   then use getTimezoneOffset   function to compute the difference then attach it to the end of string   1 Get local time with format  var local   new Date   format  yyyy-MM-ddThh mm ss      today  local time    output  2013-07-02T09 00 00   2 Get UTC time offset by hour  var offset   local getTimezoneOffset     60    output  7   3 Construct URL  time part only   var duration   local    -    offset     00     output   2013-07-02T09 00 00-7 00   The above output means my local time is 2013 07 02 9am and difference from UTC is 7 hours  UTC is 7 hours ahead of local time   So far it seems to work but what if getTimezoneOffset   returns negative value like -120   I m wondering how the format should look like in such case because I cannot figure out from W3C document  Thanks in advance

User · Accepted Answer

The below should work properly  and for all browsers  thanks to  MattJohnson for the tip    x000D   x000D  Date prototype toIsoString   function     x000D      var tzo   -this getTimezoneOffset    x000D          dif   tzo  gt   0          -   x000D          pad   function num    x000D              var norm   Math floor Math abs num    x000D              return  norm  lt  10    0          norm  x000D             x000D      return this getFullYear     x000D           -    pad this getMonth     1    x000D           -    pad this getDate      x000D           T    pad this getHours      x000D                pad this getMinutes      x000D                pad this getSeconds      x000D          dif   pad tzo   60    x000D                pad tzo   60   x000D    x000D   x000D  var dt   new Date    x000D  console log dt toIsoString     x000D   x000D   x000D

User · Answer

No moment js needed  Here s a full round trip answer  from an input type of  datetime-local  which outputs an ISOLocal string to UTCseconds at GMT and back    lt input type  datetime-local  value  2020-02-16T19 30  gt   isoLocal  2020-02-16T19 30  utcSeconds new Date isoLocal  getTime   1000    here you have 1581899400 for utcSeconds  let isoLocal new Date utcSeconds 1000-new Date   getTimezoneOffset   60000  toISOString   substring 0 16  2020-02-16T19 30

User · Answer

getTimezoneOffset   returns the opposite sign of the format required by the spec that you referenced   This format is also known as ISO8601  or more precisely as RFC3339   In this format  UTC is represented with a Z while all other formats are represented by an offset from UTC   The meaning is the same as JavaScript s  but the order of subtraction is inverted  so the result carries the opposite sign   Also  there is no method on the native Date object called format  so your function in  1 will fail unless you are using a library to achieve this   Refer to this documentation   If you are seeking a library that can work with this format directly  I recommend trying moment js   In fact  this is the default format  so you can simply do this   var m   moment          get  now  as a moment var s   m format        the ISO format is the default so no parameters are needed     sample output    2013-07-01T17 55 13-07 00   This is a well-tested  cross-browser solution  and has many other useful features

User · Answer

I think it is worth considering that you can get the requested info with just a single API call to the standard library     new Date   toLocaleString   sv     timeZoneName   short           produces  2019-10-30 15 33 47 GMT-4    You would have to do text swapping if you want to add the  T  delimiter  remove the  GMT-   or append the   00  to the end   But then you can easily play with the other options if you want to eg  use 12h time or omit the seconds etc   Note that I m using Sweden as locale because it is one of the countries that uses ISO 8601 format   I think most of the ISO countries use this  GMT-4  format for the timezone offset other then Canada which uses the time zone abbreviation eg   EDT  for eastern-daylight-time   You can get the same thing from the newer standard i18n function  Intl DateTimeFormat     but you have to tell it to include the time via the options or it will just give date

User · Answer

You can achieve this with a few simple extension methods  The following Date extension method returns just the timezone component in ISO format  then you can define another for the date time part and combine them for a complete date-time-offset string  Date prototype getISOTimezoneOffset   function          const offset   this getTimezoneOffset        return  offset  lt  0    quot   quot     quot - quot     Math floor Math abs offset   60   leftPad 2     quot   quot     Math abs offset   60   leftPad 2      Date prototype toISOLocaleString   function          return this getFullYear      quot - quot     this getMonth     1  leftPad 2     quot - quot            this getDate   leftPad 2     quot T quot    this getHours   leftPad 2     quot   quot            this getMinutes   leftPad 2     quot   quot    this getSeconds   leftPad 2     quot   quot            this getMilliseconds   leftPad 3      Number prototype leftPad   function  size        var s   String this       while  s length  lt   size    2             s    quot 0 quot    s            return s     Example usage  var date   new Date    console log date toISOLocaleString     date getISOTimezoneOffset        Prints  quot 2020-08-05T16 15 46 525 10 00 quot   I know it s 2020 and most people are probably using Moment js by now  but a simple copy  amp  pastable solution is still sometimes handy to have   The reason I split the date time and offset methods is because I m using an old Datejs library which already provides a flexible toString method with custom format specifiers  but just doesn t include the timezone offset  Hence  I added toISOLocaleString for anyone without said library

User · Answer

Here are the functions I used for this end  function localToGMTStingTime localTime   null        var date   localTime   new Date localTime    new Date        return new Date date getTime      date getTimezoneOffset     60000   toISOString        function GMTToLocalStingTime GMTTime   null        var date   GMTTime   new Date GMTTime    new Date         return new Date date getTime   -  date getTimezoneOffset     60000   toISOString

User · Answer

Check this   function dateToLocalISO date        const off      date getTimezoneOffset       const absoff   Math abs off      return  new Date date getTime   - off 60 1000  toISOString   substr 0 23                 off  gt  0    -                         absoff   60  toFixed 0  padStart 2  0                         absoff   60  toString   padStart 2  0          Test it  d   new Date    dateToLocalISO d        gt   2019-06-21T16 07 22 181-03 00      Is similar to   moment   require  moment   moment d  format  YYYY-MM-DDTHH mm ss SSSZ          gt   2019-06-21T16 07 22 181-03 00

User · Answer

function setDate        var now   new Date        now setMinutes now getMinutes   - now getTimezoneOffset         var timeToSet   now toISOString   slice 0 16                   If you have an element called  quot eventDate quot  like the following            lt input type  quot datetime-local quot  name  quot eventdate quot  id  quot eventdate quot    gt           and you would like to  set the current and minimum time then use the following              var elem   document getElementById  quot eventDate quot        elem value   timeToSet      elem min   timeToSet

User · Answer

My answer is a slight variation for those who just want today s date in the local timezone in the YYYY-MM-DD format   Let me be clear   My Goal  get today s date in the user s timezone but formatted as ISO8601  YYYY-MM-DD   Here is the code   new Date   toLocaleDateString  sv       2020-02-23        This works because the Sweden locale uses the ISO 8601 format

User · Answer

This is my function for the clients timezone  it s lite weight and simple    function getCurrentDateTimeMySql                   var tzoffset    new Date    getTimezoneOffset     60000    offset in milliseconds       var localISOTime    new Date Date now   - tzoffset   toISOString   slice 0  19  replace  T               var mySqlDT   localISOTime        return mySqlDT

User · Answer

Just my two sends here  I was facing this issue with datetimes so what I did is this   const moment   require  moment-timezone    const date   moment tz  America Bogota   format     Then save date to db to be able to compare it from some query     To install moment-timezone  npm i moment-timezone

[javascript] How to ISO 8601 format a Date with Timezone Offset in JavaScript?

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