[javascript] convert 12-hour hh:mm AM/PM to 24-hour hh:mm

Is there any simple way to convert 12-hour hh:mm AM/PM to 24-hour hh:mm using jquery?

Note: not using any other libraries.

I have a var time = $("#starttime").val() that returns a hh:mm AM/PM.

I had to do something similar but I was generating a Date object so I ended up making a function like this:

function convertTo24Hour(time) {
    var hours = parseInt(time.substr(0, 2));
    if(time.indexOf('am') != -1 && hours == 12) {
        time = time.replace('12', '0');
    }
    if(time.indexOf('pm')  != -1 && hours < 12) {
        time = time.replace(hours, (hours + 12));
    }
    return time.replace(/(am|pm)/, '');
}

I think this reads a little easier. You feed a string in the format h:mm am/pm.

    var time = convertTo24Hour($("#starttime").val().toLowerCase());
    var date = new Date($("#startday").val() + ' ' + time);

Examples:

        $("#startday").val('7/10/2013');

        $("#starttime").val('12:00am');
        new Date($("#startday").val() + ' ' + convertTo24Hour($("#starttime").val().toLowerCase()));
        Wed Jul 10 2013 00:00:00 GMT-0700 (PDT)

        $("#starttime").val('12:00pm');
        new Date($("#startday").val() + ' ' + convertTo24Hour($("#starttime").val().toLowerCase()));
        Wed Jul 10 2013 12:00:00 GMT-0700 (PDT)

        $("#starttime").val('1:00am');
        new Date($("#startday").val() + ' ' + convertTo24Hour($("#starttime").val().toLowerCase()));
        Wed Jul 10 2013 01:00:00 GMT-0700 (PDT)

        $("#starttime").val('12:12am');
        new Date($("#startday").val() + ' ' + convertTo24Hour($("#starttime").val().toLowerCase()));
        Wed Jul 10 2013 00:12:00 GMT-0700 (PDT)

        $("#starttime").val('3:12am');
        new Date($("#startday").val() + ' ' + convertTo24Hour($("#starttime").val().toLowerCase()));
        Wed Jul 10 2013 03:12:00 GMT-0700 (PDT)

        $("#starttime").val('9:12pm');
        new Date($("#startday").val() + ' ' + convertTo24Hour($("#starttime").val().toLowerCase()));
        Wed Jul 10 2013 21:12:00 GMT-0700 (PDT)

Short ES6 code

const convertFrom12To24Format = (time12) => {
  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}`;
}

const convertFrom24To12Format = (time24) => {
  const [sHours, minutes] = time24.match(/([0-9]{1,2}):([0-9]{2})/).slice(1);
  const period = +sHours < 12 ? 'AM' : 'PM';
  const hours = +sHours % 12 || 12;

  return `${hours}:${minutes} ${period}`;
}

Converting AM/PM Time string to 24 Hours Format. Example 9:30 PM to 21:30

function get24HrsFrmAMPM(timeStr) {
    if (timeStr && timeStr.indexOf(' ') !== -1 && timeStr.indexOf(':') !== -1) {
        var hrs = 0;
        var tempAry = timeStr.split(' ');
        var hrsMinAry = tempAry[0].split(':');
        hrs = parseInt(hrsMinAry[0], 10);
        if ((tempAry[1] == 'AM' || tempAry[1] == 'am') && hrs == 12) {
            hrs = 0;
        } else if ((tempAry[1] == 'PM' || tempAry[1] == 'pm') && hrs != 12) {
            hrs += 12;
        }
        return ('0' + hrs).slice(-2) + ':' + ('0' + parseInt(hrsMinAry[1], 10)).slice(-2);
    } else {
        return null;
    }
}

date --date="2:00:01 PM" +%T
14:00:01

date --date="2:00 PM" +%T | cut -d':' -f1-2
14:00

var="2:00:02 PM"
date --date="$var" +%T
14:00:02

 var time = "9:09:59AM"
    var pmCheck =time.includes("PM");
    var hrs=parseInt(time.split(":")[0]);
    var newtime='';
    // this is for between  12 AM to 12:59:59AM  = 00:00:00
    if( hrs == 12  && pmCheck == false){
        newtime= "00" +':'+ time.split(":")[1] +':'+ time.split(":")[2].replace("AM",'');
        }
    //this is for between  12 PM to 12:59:59 =12:00:00
    else if (hrs == 12  && pmCheck == true){
             newtime= "12" +':'+ time.split(":")[1] +':'+ time.split(":")[2].replace("PM",'');
    }
    //this is for between 1 AM and 11:59:59 AM
    else if (!pmCheck){
        newtime= hrs +':'+ time.split(":")[1] +':'+ time.split(":")[2].replace("AM",'');
    }
    //this is for between 1 PM and 11:59:59 PM
    else if(pmCheck){
        newtime= (hrs +12)+':'+ time.split(":")[1] +':'+ time.split(":")[2].replace("PM",'');
    }
    console.log(newtime);

I just solved this issue on HackerRank, so I'm here to share my result

function timeConversion(s) {
    const isPM = s.indexOf('PM') !== -1;
    let [hours, minutes, seconds] = s.replace(isPM ? 'PM':'AM', '').split(':');

    if (isPM) {
        hours = parseInt(hours, 10) + 12;
        hours = hours === 24 ? 12 : hours;
    } else {
        hours = parseInt(hours, 10);
        hours = hours === 12 ? 0 : hours;
        if (String(hours).length === 1) hours = '0' + hours;
    }

    const time = [hours, minutes, seconds].join(':');

    return time;
}

This works for inputs like 06:40:03AM.

I've created a bit of an adaptation of script @devnull69 submitted. I felt for my application it would be more useful as a function that returned the value that I could, then use as a variable.

HTML

<input type="text" id="time_field" />
<button>Submit</submit>

jQuery

$(document).ready(function() {

    function convertTime(time) {

        var hours = Number(time.match(/^(\d\d?)/)[1]);
        var minutes = Number(time.match(/:(\d\d?)/)[1]);
        var AMPM = time.match(/\s(AM|PM)$/i)[1];

        if((AMPM == 'PM' || AMPM == 'pm') && hours < 12) {
            hours = hours + 12;
        }
        else if((AMPM == 'AM' || AMPM == "am") && hours == 12) {
            hours = hours - 12;
        }

        var sHours = hours.toString();
        var sMinutes = minutes.toString();

        if(hours < 10) {
            sHours = "0" + sHours;
        }
        else if(minutes < 10) {
             sMinutes = "0" + sMinutes;
        }

        return sHours + ":" + sMinutes;

    }

    $('button').click(function() {
        alert(convertTime($('#time_field').val()));
    });

});

function timeConversion(s) {
  var time = s.toLowerCase().split(':');
  var hours = parseInt(time[0]);
  var _ampm = time[2];
  if (_ampm.indexOf('am') != -1 && hours == 12) {
    time[0] = '00';
  }
  if (_ampm.indexOf('pm')  != -1 && hours < 12) {
    time[0] = hours + 12;
  }
  return time.join(':').replace(/(am|pm)/, '');
}

Call the function with string params:

timeConversion('17:05:45AM')

or

timeConversion('07:05:45PM')

You could try this more generic function:

function from12to24(hours, minutes, meridian) {
  let h = parseInt(hours, 10);
  const m = parseInt(minutes, 10);
  if (meridian.toUpperCase() === 'PM') {
    h = (h !== 12) ? h + 12 : h;
  } else {
    h = (h === 12) ? 0 : h;
  }
  return new Date((new Date()).setHours(h,m,0,0));
}   

Note it uses some ES6 functionality.

In case you're looking for a solution that converts ANY FORMAT to 24 hours HH:MM correctly.

function get24hTime(str){
    str = String(str).toLowerCase().replace(/\s/g, '');
    var has_am = str.indexOf('am') >= 0;
    var has_pm = str.indexOf('pm') >= 0;
    // first strip off the am/pm, leave it either hour or hour:minute
    str = str.replace('am', '').replace('pm', '');
    // if hour, convert to hour:00
    if (str.indexOf(':') < 0) str = str + ':00';
    // now it's hour:minute
    // we add am/pm back if striped out before 
    if (has_am) str += ' am';
    if (has_pm) str += ' pm';
    // now its either hour:minute, or hour:minute am/pm
    // put it in a date object, it will convert to 24 hours format for us 
    var d = new Date("1/1/2011 " + str);
    // make hours and minutes double digits
    var doubleDigits = function(n){
        return (parseInt(n) < 10) ? "0" + n : String(n);
    };
    return doubleDigits(d.getHours()) + ':' + doubleDigits(d.getMinutes());
}

console.log(get24hTime('6')); // 06:00
console.log(get24hTime('6am')); // 06:00
console.log(get24hTime('6pm')); // 18:00
console.log(get24hTime('6:11pm')); // 18:11
console.log(get24hTime('6:11')); // 06:11
console.log(get24hTime('18')); // 18:00
console.log(get24hTime('18:11')); // 18:11

Tested for all the use cases

function timeConversion(s) {
let h24;
let m24;
let sec24;

const splittedDate = s.split(":");
const h = parseInt(splittedDate[0], 10);
const m = parseInt(splittedDate[1], 10);
const sec = parseInt(splittedDate[2][0] + splittedDate[2][1], 10); 
const meridiem = splittedDate[2][2] + splittedDate[2][3];

if (meridiem === "AM") {
    if (h === 12) {
        h24 = '00';
    } else {
        h24 = h;
        if (h24 < 10) {
            h24 = '0' + h24;
        }
    }
    m24 = m;
    sec24 = sec;
} else if (meridiem === "PM") {
    if (h === 12) {
        h24 = h
    } else {
        h24 = h + 12;
        if (h24 < 10) {
            h24 = '0' + h24;
        }
    }
    m24 = m;
    sec24 = sec;
}


if (m24 < 10) {
    m24 = '0' + m24; 
} 

if (sec24 < 10) {
    sec24 = '0' + sec24;
}

  return h24 + ":" + m24 + ":" + sec24; 
}

Here is the jsfiddle working example

based on meeting CodeSkill #1

validation of format should be another function :)

  _x000D_
_x000D_
function convertTimeFrom12To24(timeStr) {_x000D_
  var colon = timeStr.indexOf(':');_x000D_
  var hours = timeStr.substr(0, colon),_x000D_
      minutes = timeStr.substr(colon+1, 2),_x000D_
      meridian = timeStr.substr(colon+4, 2).toUpperCase();_x000D_
 _x000D_
  _x000D_
  var hoursInt = parseInt(hours, 10),_x000D_
      offset = meridian == 'PM' ? 12 : 0;_x000D_
  _x000D_
  if (hoursInt === 12) {_x000D_
    hoursInt = offset;_x000D_
  } else {_x000D_
    hoursInt += offset;_x000D_
  }_x000D_
  return hoursInt + ":" + minutes;_x000D_
}_x000D_
console.log(convertTimeFrom12To24("12:00 AM"));_x000D_
console.log(convertTimeFrom12To24("12:00 PM"));_x000D_
console.log(convertTimeFrom12To24("11:00 AM"));_x000D_
console.log(convertTimeFrom12To24("01:00 AM"));_x000D_
console.log(convertTimeFrom12To24("01:00 PM"));

Here my solution including seconds:

function convert_to_24h(time_str) {
    // Convert a string like 10:05:23 PM to 24h format, returns like [22,5,23]
    var time = time_str.match(/(\d+):(\d+):(\d+) (\w)/);
    var hours = Number(time[1]);
    var minutes = Number(time[2]);
    var seconds = Number(time[3]);
    var meridian = time[4].toLowerCase();

    if (meridian == 'p' && hours < 12) {
      hours += 12;
    }
    else if (meridian == 'a' && hours == 12) {
      hours -= 12;
    }
    return [hours, minutes, seconds];
  };

dateFormat.masks.armyTime= 'HH:MM';

now.format("armyTime");

For anybody reading this in the future, here is a simpler answer:

var s = "11:41:02PM";
var time = s.match(/\d{2}/g);
if (time[0] === "12") time[0] = "00";
if (s.indexOf("PM") > -1) time[0] = parseInt(time[0])+12;
return time.join(":");

i must recommend a library: Moment

code:

var target12 = '2016-12-08 9:32:45 PM';
console.log(moment(target12, 'YYYY-MM-DD h:m:s A').format('YYYY-MM-DD HH:mm:ss'));

Hope it helps someone.

/*
 * Complete the timeConversion function below.
 */
function timeConversion(s) {
    /*
     * Write your code here.
     */
    if(s.endsWith("PM")) s=s.substring(0, s.indexOf("PM"))+ " PM";
    if(s.endsWith("AM")) s=s.substring(0, s.indexOf("AM"))+ " AM";

    const d=new Date("2000-01-01 " + s);

    if(s.endsWith("PM") && d.getHours()<12) d.setHours(12); 
    if(s.endsWith("AM") && d.getHours()===12) d.setHours(d.getHours()-12); 

    let result= (d.getHours() < 10 ?  "0" + d.getHours(): d.getHours())+ ":"+   
    (d.getMinutes() <10 ? "0"+ d.getMinutes(): d.getMinutes()) + ":" +     
    (d.getSeconds() <10 ? "0"+ d.getSeconds(): d.getSeconds());

    return result;

}

timeConversion("07:05:45PM")
Sample Test Case
Input
07:05:45PM
Expected Output
19:05:45

This question needs a newer answer :)

const convertTime12to24 = (time12h) => {_x000D_
  const [time, modifier] = time12h.split(' ');_x000D_
_x000D_
  let [hours, minutes] = time.split(':');_x000D_
_x000D_
  if (hours === '12') {_x000D_
    hours = '00';_x000D_
  }_x000D_
_x000D_
  if (modifier === 'PM') {_x000D_
    hours = parseInt(hours, 10) + 12;_x000D_
  }_x000D_
_x000D_
  return `${hours}:${minutes}`;_x000D_
}_x000D_
_x000D_
console.log(convertTime12to24('01:02 PM'));_x000D_
console.log(convertTime12to24('05:06 PM'));_x000D_
console.log(convertTime12to24('12:00 PM'));_x000D_
console.log(convertTime12to24('12:00 AM'));

This will help :

 function getTwentyFourHourTime(amPmString) { 
        var d = new Date("1/1/2013 " + amPmString); 
        return d.getHours() + ':' + d.getMinutes(); 
    }

Example :

getTwentyFourHourTime("8:45 PM"); // "20:45"
getTwentyFourHourTime("8:45 AM"); // "8:45"

Update : Note : There should be a space for timestring between "Time" and "am/pm".

single and easy js function for calc time meridian in real time

JS

   function convertTime24to12(time24h) {
                var timex = time24h.split(':');

                if(timex[0] !== undefined && timex [1] !== undefined)
                 {
                     var hor = parseInt(timex[0]) > 12 ? (parseInt(timex[0])-12) : timex[0] ;
                     var minu = timex[1];
                     var merid = parseInt(timex[0]) < 12 ? 'AM' : 'PM';

                     var res = hor+':'+minu+' '+merid;

                     document.getElementById('timeMeridian').innerHTML=res.toString();
                 }
            }

Html

 <label for="end-time">Hour <i id="timeMeridian"></i> </label>
            <input type="time" name="hora" placeholder="Hora" id="end-time" class="form-control" onkeyup="convertTime24to12(this.value)">

An extended version of @krzysztof answer with the ability to work on time that has space or not between time and modifier.

const convertTime12to24 = (time12h) => {
      const [fullMatch, time, modifier] = time12h.match(/(\d?\d:\d\d)\s*(\w{2})/i);

      let [hours, minutes] = time.split(':');

      if (hours === '12') {
        hours = '00';
      }

      if (modifier === 'PM') {
        hours = parseInt(hours, 10) + 12;
      }

      return `${hours}:${minutes}`;
    }

    console.log(convertTime12to24('01:02 PM'));
    console.log(convertTime12to24('05:06 PM'));
    console.log(convertTime12to24('12:00 PM'));
    console.log(convertTime12to24('12:00 AM'));

#include <bits/stdc++.h>

using namespace std;

int main(){
    string time;
    int hours,seconds,minutes;
    string merid;
    char delim;
    stringstream ss;

    cin >> time;
    ss << time;
    ss >> hours >> delim >> minutes >> delim >> seconds >> merid;

    if((merid=="PM"&&hours!=12)||(merid=="AM"&&hours==12))
        hours=(hours+12)%24;

    printf("%02d:%02d:%02d", hours, minutes, seconds);

    return 0;
}

  function getDisplayDatetime() {
    var d = new Date("February 04, 2011 19:00"),
     hh = d.getHours(),  mm = d.getMinutes(),  dd = "AM", h = hh;
    mm=(mm.toString().length == 1)? mm = "0" + mm:mm;
    h=(h>=12)?hh-12:h;
     dd=(hh>=12)?"PM":"AM";
    h=(h == 0)?12:h;
    var textvalue=document.getElementById("txt");
    textvalue.value=h + ":" + mm + " " + dd;
}

</script>
</head>
<body>
<input type="button" value="click" onclick="getDisplayDatetime()">
<input type="text" id="txt"/>

I needed this function for a project. I tried devnull69's but I was having some trouble, mostly because the string input is very specific for the am/pm section and I would've needed to change my validation. I messed around with Adrian P.'s jsfiddle and ended up with a version that seems to work better for a larger variety of date formats. Here is the fiddle: http://jsfiddle.net/u91q8kmt/2/.

Here is the function:

function ConvertTimeformat(format, str) {
    var hours = Number(str.match(/^(\d+)/)[1]);
    var minutes = Number(str.match(/:(\d+)/)[1]);
    var AMPM = str.match(/\s?([AaPp][Mm]?)$/)[1];
    var pm = ['P', 'p', 'PM', 'pM', 'pm', 'Pm'];
    var am = ['A', 'a', 'AM', 'aM', 'am', 'Am'];
    if (pm.indexOf(AMPM) >= 0 && hours < 12) hours = hours + 12;
    if (am.indexOf(AMPM) >= 0 && hours == 12) hours = hours - 12;
    var sHours = hours.toString();
    var sMinutes = minutes.toString();
    if (hours < 10) sHours = "0" + sHours;
    if (minutes < 10) sMinutes = "0" + sMinutes;
    if (format == '0000') {
        return (sHours + sMinutes);
    } else if (format == '00:00') {
        return (sHours + ":" + sMinutes);
    } else {
        return false;
    }
}

Typescript solution based off of @krzysztof-dabrowski 's answer

export interface HoursMinutes {
  hours: number;
  minutes: number;
}
export function convert12to24(time12h: string): HoursMinutes {
  const [time, modifier] = time12h.split(' ');
  let [hours, minutes] = time.split(':');

  if (hours === '12') {
    hours = '00';
  }

  if (minutes.length === 1) {
    minutes = `0${minutes}`;
  }

  if (modifier.toUpperCase() === 'PM') {
    hours = parseInt(hours, 10) + 12 + '';
  }

  return {
    hours: parseInt(hours, 10),
    minutes: parseInt(minutes, 10)
  };
}

With this you can have the following: Sample Input: 07:05:45PM Sample Output: 19:05:45

function timeConversion(s) {
    let output = '';
    const timeSeparator = ':'
    const timeTokenType = s.substr(s.length - 2 , 2).toLowerCase();
    const timeArr = s.split(timeSeparator).map((timeToken) => {
    const isTimeTokenType = 
          timeToken.toLowerCase().indexOf('am') > 0 ||                                                                                               
           timeToken.toLowerCase().indexOf('pm');
        if(isTimeTokenType){
            return timeToken.substr(0, 2);
        } else {
            return timeToken;
        }
    });
    const hour = timeArr[0];
    const minutes = timeArr[1];
    const seconds = timeArr[2];
    const hourIn24 = (timeTokenType === 'am') ? parseInt(hour) - 12 : 
    parseInt(hour) + 12;
    return hourIn24.toString()+ timeSeparator + minutes + timeSeparator + seconds;
}

Hope you like it !

function convertTo24Hour(time) {
    time = time.toUpperCase();
    var hours = parseInt(time.substr(0, 2));
    if(time.indexOf('AM') != -1 && hours == 12) {
        time = time.replace('12', '0');
    }
    if(time.indexOf('PM')  != -1 && hours < 12) {
        time = time.replace(hours, (hours + 12));
    }
    return time.replace(/(AM|PM)/, '');
}