get client time zone from browser

Question

Is there a reliable way to get a timezone from client browser  I saw the following links but I want a more robust solution    Auto detect a time zone with JavaScript  Timezone detection in JavaScript

User · Answer

No  There is no single reliable way and there will never be  Did you really think you could trust the client

User · Answer

Often when people are looking for  timezones   what will suffice is just  UTC offset   e g   their server is in UTC 5 and they want to know that their client is running in UTC-8     In plain old javascript  new Date    getTimezoneOffset   60 will return the current number of hours offset from UTC   It s worth noting a possible  gotcha  in the sign of the getTimezoneOffset   return value  from MDN docs        The time-zone offset is the difference  in minutes  between UTC and local time  Note that 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 10 00  Australian Eastern Standard Time  Vladivostok Time  Chamorro Standard Time   -600 will be returned      However  I recommend you use the day js for time date related Javascript code  In which case you can get an ISO 8601 formatted UTC offset by running    gt  dayjs   format  Z    -08 00    It probably bears mentioning that the client can easily falsify this information    Note  this answer originally recommended https   momentjs com   but dayjs is a more modern  smaller alternative

User · Answer

you could use moment-timezone to guess the timezone    gt  moment tz guess    America Asuncion

User · Answer

I used an approach similar to the one taken by Josh Fraser  which determines the browser time offset from UTC and whether it recognizes DST or not  but somewhat simplified from his code    var ClientTZ         UTCoffset   0              Browser time offset from UTC in minutes     UTCoffsetT    0000S        Browser time offset from UTC in    hhmmD  form     hasDST      false          Browser time observes DST         Determine browser s timezone and DST     getBrowserTZ  function              var self   ClientTZ              Determine UTC time offset         var now   new Date            var date1   new Date now getFullYear    1-1  1  0  0  0  0         Jan         var diff1   -date1 getTimezoneOffset            self UTCoffset   diff1              Determine DST use         var date2   new Date now getFullYear    6-1  1  0  0  0  0         Jun         var diff2   -date2 getTimezoneOffset            if  diff1    diff2                self hasDST   true              if  diff1 - diff2  gt   0                  self UTCoffset   diff2         East of GMT                       Convert UTC offset to   hhmmD form         diff2    diff1  lt  0   -diff1   diff1    60          var hr   Math floor diff2           var min   diff2 - hr          diff2   hr   100   min   60          self UTCoffsetT    diff1  lt  0    -            hr  lt  10    0          diff2 toString      self hasDST    D     S             return self UTCoffset               Onload ClientTZ getBrowserTZ      Upon loading  the ClientTZ getBrowserTZ   function is executed  which sets    ClientTZ UTCoffset to the browser time offset from UTC in minutes  e g   CST is -360 minutes  which is -6 0 hours from UTC   ClientTZ UTCoffsetT to the offset in the form    hhmmD   e g    -0600D    where the suffix is D for DST and S for standard  non-DST   ClientTZ hasDST  to true or false     The ClientTZ UTCoffset is provided in minutes instead of hours  because some timezones have fractional hourly offsets  e g    0415    The intent behind ClientTZ UTCoffsetT is to use it as a key into a table of timezones  not provided here   such as for a drop-down  lt select gt  list

User · Answer

For now  the best bet is probably jstz as suggested in mbayloon s answer   For completeness  it should be mentioned that there is a standard on it s way  Intl  You can see this in Chrome already    gt  Intl DateTimeFormat   resolvedOptions   timeZone  America Los Angeles     This doesn t actually follow the standard  which is one more reason to stick with the library

User · Answer

Look at this repository pageloom it is helpful  download jstz min js and add a function to your html page    lt script language  javascript  gt      function getTimezoneName             timezone   jstz determine           return timezone name           lt  script gt    and call this function from your display tag

User · Answer

Here is a version that works well in September 2020 using fetch and https   worldtimeapi org api  x000D   x000D  fetch  https   worldtimeapi org api ip      then response   gt  response json       then data   gt  console log data timezone data datetime data dst    x000D   x000D   x000D

User · Answer

Half a decade later we have a built-in way for it   For modern browsers I would use    x000D   x000D  const tz   Intl DateTimeFormat   resolvedOptions   timeZone  x000D  console log tz   x000D   x000D   x000D    This returns a IANA timezone string  but not the offset  Learn more at the MDN reference   Compatibility table - as of March 2019  works for 90  of the browsers in use globally  Doesn t work on Internet Explorer

User · Answer

Here is a jsfiddle   It provides the abbreviation of the current user timezone    Here is the code sample   var tz   jstz determine    console log tz name     console log moment tz zone tz name    abbr new Date   getTime

[javascript] get client time zone from browser

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