Javascript convert 24-hour time-of-day string to 12-hour time with AM PM and no timezone

Question

The server is sending a string in this format  18 00 00  This is a time-of-day value independent of any date  How to convert it to 6 00PM in Javascript  I could prepend today s date as a string to the value sent by the server and then parse the combined values and then try the  toTimeString   method of the Date object  but the format that time method emits is 24-hour time with a seconds chunk  I could write a function  but is there something built in

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Nothing built in  my solution would be as follows    function tConvert  time         Check correct time format and split into components   time   time toString    match      01  d 2 0-3       0-5  d    0-5  d          time      if  time length  gt  1       If time format correct     time   time slice  1       Remove full string match value     time 5     time 0   lt  12    AM     PM      Set AM PM     time 0     time 0    12    12     Adjust hours       return time join          return adjusted time or original string    tConvert   18 00 00      This function uses a regular expression to validate the time string and to split it into its component parts  Note also that the seconds in the time may optionally be omitted  If a valid time was presented  it is adjusted by adding the AM PM indication and adjusting the hours    The return value is the adjusted time if a valid time was presented or the original string    Working example   x000D   x000D   function     x000D   x000D    function tConvert time    x000D         Check correct time format and split into components x000D      time   time toString   match     01  d 2 0-3       0-5  d    0-5  d          time   x000D   x000D      if  time length  gt  1       If time format correct x000D        time   time slice 1      Remove full string match value x000D        time 5     time 0   lt  12    AM     PM      Set AM PM x000D        time 0     time 0    12    12     Adjust hours x000D        x000D      return time join         return adjusted time or original string x000D      x000D   x000D    var tel   document getElementById  tests    x000D   x000D    tel innerHTML   tel innerHTML split   r  n  n r   r   map function v    x000D      return v   v       gt       tConvert v trim            v  x000D       join   n    x000D        x000D   lt h3 gt tConvert tests    lt  h3 gt  x000D   lt pre id  tests  gt  x000D    18 00 00 x000D    18 00 x000D    00 00 x000D    11 59 01 x000D    12 00 00 x000D    13 01 57 x000D    24 00 x000D    sdfsdf x000D    12 61 54 x000D   lt  pre gt  x000D   x000D   x000D

User · Answer

Make sure that your time is in this format HH MM SS PM AM   function timeConversion s         s   s split           var time   s 2       if time charAt 2       A   amp  amp  parseInt s 0      12  s 0     00       if time charAt 2       P   amp  amp  parseInt s 0    lt 12  s 0    parseInt s 0   12      if s 0   gt  24  s 0 - 24      var x   time split     slice 0 2       s 2    x join          console log s join

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Short ES6 code  const convertFrom24To12Format    time24    gt      const  sHours  minutes    time24 match    0-9  1 2     0-9  2     slice 1     const period    sHours  lt  12    AM     PM     const hours    sHours   12    12     return    hours    minutes    period        const convertFrom12To24Format    time12    gt      const  sHours  minutes  period    time12 match    0-9  1 2     0-9  2    AM PM    slice 1     const PM   period      PM     const hours     sHours   12     PM   12   0      return      0    hours  slice -2     minutes

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Assuming you will get the date string in a proper format  I have a solution   function parseDateTime dt            var date   false          if  dt                var c date   new Date dt               var hrs   c date getHours                var min   c date getMinutes                if  isNaN hrs     isNaN min     c date      Invalid Date                     return null                            var type    hrs  lt   12      AM      PM               date      hrs   12     hrs          min   type                    return date             parseDateTime  2016-11-21 12 39 08      12 39 AM      parseDateTime  2017-11-21 23 39 08      11 39 PM

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Researching this same question I have come across several complicated  hard to understand solutions  and then it dawned on me   There is a very simple solution that doesn t rely on hard-to-read regular expressions or other complicated code   Unless I am missing something obvious  this is an extremely simple  easy to understand solution     function timeTo12HrFormat time         Take a time in 24 hour format and format it in 12 hour format     var time part array   time split           var ampm    AM        if  time part array 0   gt   12            ampm    PM              if  time part array 0   gt  12            time part array 0    time part array 0  - 12             formatted time   time part array 0          time part array 1          time part array 2          ampm       return formatted time       var time   timeTo12HrFormat 18 00 00   console log time       6 00 00 PM

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It will be better to use momentjs Just a little conversation  quot 2 PM quot  to  quot 14 00 quot  const number   moment  quot 02 00 PM quot     quot h mm A quot    format  quot HH mm quot    cosole log number         quot 14 00 quot   quot 14 00 quot  to  quot 2 PM quot  const number   moment  quot 14 00 quot     quot HH mm quot    format  quot hh mm a quot    cosole log number       quot 02 00 pm quot

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Here s a few variations that will work    x000D   x000D  const oneLiner    hour    00   min    00   sec    00     gt      hour   12     12      0    min  slice -2     sec     hour  lt  12     am     pm    x000D  console log  oneliner   oneLiner     13 05 12  split        x000D   x000D   x000D   x000D  const oneLinerWithObjectInput     hour    00   min    00   sec    00           gt      hour   12     12      0    min  slice -2     sec     hour  lt  12     am     pm    x000D  console log  onelinerWithObjectInput   oneLinerWithObjectInput   x000D     hour   13 05 12  split      0   x000D     min   13 05 12  split      1   x000D     sec   13 05 12  split      2  x000D      x000D   x000D   x000D  const multiLineWithObjectInput     hour    00   min    00   sec    00           gt    x000D     const newHour    hour   12     12 x000D           newMin      0    min  slice -2  x000D           ampm       hour  lt  12     am     pm  x000D     return    newHour    newMin    sec    ampm   x000D    x000D  console log  multiLineWithObjectInput   multiLineWithObjectInput   x000D     hour   13 05 12  split      0   x000D     min   13 05 12  split      1   x000D     sec   13 05 12  split      2  x000D      x000D   x000D   x000D

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function timeConversion s        let hour   parseInt s substring 0 2        hour   s indexOf  AM    gt  - 1  amp  amp  hour     12    00    hour      hour   s indexOf  PM    gt  - 1  amp  amp  hour     12   hour   12   hour      hour   hour  lt  10  amp  amp  hour  gt  0    0  hour   hour       return hour   s substring 2 8

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A simple code for this will be   time   time split         here the time is like  16 14  let meridiemTime   time 0   gt   12  amp  amp   time 0 -12    12          time 1      PM      Number time 0      12          time 1      AM     You can adjust according to your time format

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function timeformat date1      var date new Date date1     var month   date toLocaleString  en-us     month   long        var mdate   date getDate      var year   date getFullYear      var hours   date getHours      var minutes   date getMinutes      var ampm   hours  gt   12    pm     am     hours   hours   12    hours   hours   hours   12     the hour  0  should be  12    minutes   minutes  lt  10    0  minutes   minutes    var strTime   mdate  -  month  -  year     hours         minutes         ampm    return strTime    var ampm timeformat  2019-01-11 12 26 43    console log ampm     Here the Function to Convert time into am or pm with Date it may be help Someone

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This might help to format if you are using ES6  Below code snippet will ignore the seconds  If you want to consider seconds you can add that as the first parameter       const formatFrom24Hrsto12Hrs    time  ignoreZero   true    gt          let  hours  minutes    time split            let modifier    hours  lt  12    am     pm        hours    hours   12    12       minutes   ignoreZero  amp  amp   minutes     0            minutes         return hours   minutes   modifier

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function Time Function     var date   new Date   var time     var x   AM  if date getHours    gt 12       x   PM    time  date getHours   12   x       date getMinutes         date getSeconds

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To get AM PM  Check if the hour portion is less than 12  then it is AM  else PM   To get the hour  do  hour   12     12   This should do it     var timeString    18 00 00   var H    timeString substr 0  2   var h   H   12    12  var ampm    H  lt  12    H     24     AM     PM   timeString   h   timeString substr 2  3    ampm    http   jsfiddle net Skwt7 4   That assumes that AM times are formatted as  eg  08 00 00   If they are formatted without the leading zero  you would have to test the position of the first colon   var hourEnd   timeString indexOf       var H    timeString substr 0  hourEnd   var h   H   12    12  var ampm    H  lt  12    H     24     AM     PM   timeString   h   timeString substr hourEnd  3    ampm    http   jsfiddle net Skwt7 3

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Thanks to  HBP for paving the way here   I found this to add a little flexibility to the solution   The RegEx has been updated to accommodate times before noon   This solution allows you to pass any string to it  As long as a valid time  in this format 18 00    18 00 00    3 00    3 00 00  is somewhere in that string  you re good to go   Note  you can use just the militaryToTweleveHourConverter or take the guts out of the parseTime variable  However  I m formatting a date from a database with date-fns then passing that formatted date to the converter    Totally works  Hope this helps   import dateFns from  date-fns           ---------------------------      Format ex  Sat 1 1 18 1 00pm      ---------------------------  const formatMonthDayYearTime   date   gt    militaryToTweleveHourConverter      dateFns format new Date date    ddd M DD YY H mm              -------------------------------      Convert MILITARY TIME to 12 hour      -------------------------------  const militaryToTweleveHourConverter   time   gt      const getTime   time split          const parseTime   getTime map res   gt           Check for correct time format and split into components or return non-time units unaltered     let timeUnit   res        toString          match      d   0-1  d 2 0-3       0-5  d    0-5  d          res        console log  timeUnit   timeUnit          If the time format is matched  it will break the components into an array        ie    19 00    19         00   undefined      if  timeUnit length  gt  1             Remove full string match value       timeUnit   timeUnit slice 1            Set am pm and assign it to the last index in the array       timeUnit 5    timeUnit 0   lt  12    am     pm            Adjust hours by subtracting 12 from anything greater than 12 and replace the value in the hours index       timeUnit 0    timeUnit 0    12    12               return adjusted time or original string     return timeUnit join                 Re-assemble the array pieces into a string   return parseTime join            console log formatMonthDayYearTime  Sat 9 17 18 18 30        console log returns the following    Mon 9 17 18 6 30pm  console log militaryToTweleveHourConverter  18 30        console log returns the following    6 30pm  console log militaryToTweleveHourConverter  18 30 09        console log returns the following    6 30 09pm  console log militaryToTweleveHourConverter  8 30 09        console log returns the following    8 30 09am

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Here s my way using if statements    x000D   x000D  const converTime    time    gt    x000D    let hour    time split       0  x000D    let min    time split       1  x000D    let part   hour  gt  12    pm     am   x000D     x000D    min    min     length    1    0  min     min  x000D    hour   hour  gt  12   hour - 12   hour  x000D    hour    hour     length    1    0  hour     hour  x000D   x000D    return     hour    min    part    x000D    x000D   x000D  console log converTime  18 00 00    x000D  console log converTime  6 5 00    x000D   x000D   x000D

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Based on gilly3 s answer   If you want to convert    08 00 to 08 00 AM   16 00 to 04 00 PM   Then this will work   function tConv24 time24      var ts   time24    var H    ts substr 0  2     var h    H   12     12    h    h  lt  10    0  h  h      leading 0 at the left for 1 digit hours   var ampm   H  lt  12     AM      PM     ts   h   ts substr 2  3    ampm    return ts       https   jsfiddle net fpjs9g0L

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toLocaleTimeString   makes this very simple  There is no need to do this yourself anymore  You ll be happier and live longer if you don t attack dates with string methods    x000D   x000D  const timeString    18 00 00  x000D     Append any date  Use your birthday  x000D  const timeString12hr   new Date  1970-01-01T    timeString    Z   x000D     toLocaleTimeString     x000D       timeZone  UTC  hour12 true hour  numeric  minute  numeric   x000D       x000D  document getElementById  myTime   innerText   timeString12hr x000D   lt h1 id  myTime  gt  lt  h1 gt  x000D   x000D   x000D

[javascript] Javascript: convert 24-hour time-of-day string to 12-hour time with AM/PM and no timezone

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