[javascript] Converting 24 hour time to 12 hour time w/ AM & PM using Javascript

What is the best way to convert the following JSON returned value from a 24-hour format to 12-hour format w/ AM & PM? The date should stay the same - the time is the only thing that needs formatting.

February 04, 2011 19:00:00

P.S. Using jQuery if that makes it any easier! Would also prefer a simple function/code and not use Date.js.

This way you have more control over the output - i.e - if you wanted the time format to be '4:30 pm' instead of '04:30 P.M.' - you can convert to whatever format you decide you want - and change it later too. Instead of being constrained to some old method that does not allow any flexibility.

and you only need to convert the first 2 digits as the minute and seconds digits are the same in 24 hour time or 12 hour time.

var my_time_conversion_arr = {'01':"01", '02':"02", '03':"03", '04':"04", '05':"05", '06':"06", '07':"07", '08':"08", '09':"09", '10':"10", '11':"11", '12': "12", '13': "1", '14': "2", '15': "3", '16': "4", '17': "5", '18': "6", '19': "7", '20': "8", '21': "9", '22': "10", '23': "11", '00':"12"};

                var AM_or_PM = "";
                var twenty_four_hour_time = "16:30";
                var twenty_four_hour_time_arr = twenty_four_hour_time.split(":");
                var twenty_four_hour_time_first_two_digits = twenty_four_hour_time_arr[0];

                var first_two_twelve_hour_digits_converted = my_time_conversion_arr[twenty_four_hour_time_first_two_digits];

                var time_strng_to_nmbr = parseInt(twenty_four_hour_time_first_two_digits);
                if(time_strng_to_nmbr >12){
                    //alert("GREATER THAN 12");
                    AM_or_PM = "pm";
                }else{
                    AM_or_PM = "am";
                }

                var twelve_hour_time_conversion = first_two_twelve_hour_digits_converted+":"+twenty_four_hour_time_arr[1]+" "+AM_or_PM;

You can take a look at this. One of the examples says:

var d = new Date(dateString);

Once you have Date object you can fairly easy play with it. You can either call toLocaleDateString, toLocaleTimeString or you can test if getHours is bigger than 12 and then just calculate AM/PM time.

var dt = new Date();
    var h =  dt.getHours(), m = dt.getMinutes();
    var thistime = (h > 12) ? (h-12 + ':' + m +' PM') : (h + ':' + m +' AM');
console.log(thistime);

Here is the Demo

Keep it simple and clean

var d = new Date();
var n = d.toLocaleString();

https://jsfiddle.net/rinu6200/3dkdxaad/#base

This is how you can change hours without if statement:

hours = ((hours + 11) % 12 + 1);

For anyone reading who wants ONLY the time in the output, you can pass options to JavaScript's Date::toLocaleString() method. Example:

var date = new Date("February 04, 2011 19:00:00");_x000D_
var options = {_x000D_
  hour: 'numeric',_x000D_
  minute: 'numeric',_x000D_
  hour12: true_x000D_
};_x000D_
var timeString = date.toLocaleString('en-US', options);_x000D_
console.log(timeString);

timeString will be set to:

8:00 AM

Add "second: 'numeric'" to your options if you want seconds too. For all option see this.

 function GetTime(date) {
        var currentTime = (new Date(date))
        var hours = currentTime.getHours()
        //Note: before converting into 12 hour format
        var suffix = '';
        if (hours > 11) {
            suffix += "PM";
        } else {
            suffix += "AM";
        }
        var minutes = currentTime.getMinutes()
        if (minutes < 10) {
            minutes = "0" + minutes
        }
        if (hours > 12) {
            hours -= 12;
        } else if (hours === 0) {
            hours = 12;
        }
        var time = hours + ":" + minutes + " " + suffix;
        return time;
    }

    //it is pm if hours from 12 onwards
    suffix = (hours >= 12)? 'pm' : 'am';

    //only -12 from hours if it is greater than 12 (if not back at mid night)
    hours = (hours > 12)? hours -12 : hours;

    //if 00 then it is 12 am
    hours = (hours == '00')? 12 : hours;

This function will convert in both directions: 12 to 24 hour or 24 to 12 hour

function toggle24hr(time, onoff){
    if(onoff==undefined) onoff = isNaN(time.replace(':',''))//auto-detect format
    var pm = time.toString().toLowerCase().indexOf('pm')>-1 //check if 'pm' exists in the time string
    time = time.toString().toLowerCase().replace(/[ap]m/,'').split(':') //convert time to an array of numbers
    time[0] = Number(time[0])
    if(onoff){//convert to 24 hour:
        if((pm && time[0]!=12)) time[0] += 12
        else if(!pm && time[0]==12) time[0] = '00'  //handle midnight
        if(String(time[0]).length==1) time[0] = '0'+time[0] //add leading zeros if needed
    }else{ //convert to 12 hour:
        pm = time[0]>=12
        if(!time[0]) time[0]=12 //handle midnight
        else if(pm && time[0]!=12) time[0] -= 12
    }
    return onoff ? time.join(':') : time.join(':')+(pm ? 'pm' : 'am')
}

Here's some examples:

//convert to 24 hour:
toggle24hr('12:00am')   //returns 00:00
toggle24hr('2:00pm')    //returns 14:00
toggle24hr('8:00am')    //returns 08:00
toggle24hr('12:00pm')   //returns 12:00

//convert to 12 hour:
toggle24hr('14:00')    //returns 2:00pm
toggle24hr('08:00')    //returns 8:00am
toggle24hr('12:00')    //returns 12:00pm
toggle24hr('00:00')    //returns 12:00am

//you can also force a specific format like this:
toggle24hr('14:00',1)    //returns 14:00
toggle24hr('14:00',0)    //returns 2:00pm

1) "Squared" instructions for making 24-hours became 12-hours:

var hours24 = new Date().getHours(); // retrieve current hours (in 24 mode)
var dayMode = hours24 < 12 ? "am" : "pm"; // if it's less than 12 then "am"
var hours12 = hours24 <= 12 ? (hours24 == 0 ? 12 : hours24) : hours24 - 12;
// "0" in 24-mode now becames "12 am" in 12-mode – thanks to user @Cristian
document.write(hours12 + " " + dayMode); // printing out the result of code

2) In a single line (same result with slightly different algorythm):

var str12 = (h24 = new Date().getHours()) && (h24 - ((h24 == 0)? -12 : (h24 <= 12)? 0 : 12)) + (h24 < 12 ? " am" : " pm");

Both options return string, like "5 pm" or "10 am" etc.

You're going to end up doing alot of string manipulation anyway, so why not just manipulate the date string itself?

Browsers format the date string differently.

Netscape ::: Fri May 11 2012 20:15:49 GMT-0600 (Mountain Daylight Time)

IE ::: Fri May 11 20:17:33 MDT 2012

so you'll have to check for that.

var D = new Date().toString().split(' ')[(document.all)?3:4];

That will set D equal to the 24-hour HH:MM:SS string. Split that on the colons, and the first element will be the hours.

var H = new Date().toString().split(' ')[(document.all)?3:4].split(':')[0];

You can convert 24-hour hours into 12-hour hours, but that hasn't actually been mentioned here. Probably because it's fairly CRAZY what you're actually doing mathematically when you convert hours from clocks. In fact, what you're doing is adding 23, mod'ing that by 12, and adding 1

twelveHour = ((twentyfourHour+23)%12)+1;

So, for example, you could grab the whole time from the date string, mod the hours, and display all that with the new hours.

var T = new Date().toString().split(' ')[(document.all)?3:4].split(':');
T[0] = (((T[0])+23)%12)+1;
alert(T.join(':'));

With some smart regex, you can probably pull the hours off the HH:MM:SS part of the date string, and mod them all in the same line. It would be a ridiculous line because the backreference $1 couldn't be used in calculations without putting a function in the replace.

Here's how that would look:

var T = new Date().toString().split(' ')[(document.all)?3:4].replace(/(^\d\d)/,function(){return ((parseInt(RegExp.$1)+23)%12)+1} );

Which, as I say, is ridiculous. If you're using a library that CAN perform calculations on backreferences, the line becomes:

var T = new Date().toString().split(' ')[(document.all)?3:4].replace(/(^\d\d)/, (($1+23)%12)+1);

And that's not actually out of the question as useable code, if you document it well. That line says:

Make a Date string, break it up on the spaces, get the browser-apropos part, and replace the first two-digit-number with that number mod'ed.

Point of the story is, the way to convert 24-hour-clock hours to 12-hour-clock hours is a non-obvious mathematical calculation:

You add 23, mod by 12, then add one more.

Here's a reasonably terse way to do it using a Prototype:

Date.prototype.getFormattedTime = function () {
    var hours = this.getHours() == 0 ? "12" : this.getHours() > 12 ? this.getHours() - 12 : this.getHours();
    var minutes = (this.getMinutes() < 10 ? "0" : "") + this.getMinutes();
    var ampm = this.getHours() < 12 ? "AM" : "PM";
    var formattedTime = hours + ":" + minutes + " " + ampm;
    return formattedTime;
}

Then all you have to do is convert your string value to a date and use the new method:

var stringValue = "February 04, 2011 19:00:00;
var dateValue = new Date(stringValue);
var formattedTime = dateValue.getFormattedTime();

Or in a single line:

var formattedTime = new Date("February 04, 2011 19:00:00").getFormattedTime();

I noticed there is already an answer, but I wanted to share my own solution, using pure JavaScript:

function curTime(pm) {
  var dt = new Date();
  var hr = dt.getHours(), min = dt.getMinutes(), sec = dt.getSeconds();
  var time = (pm ? ((hr+11)%12+1) : (hr<10?'0':'')+hr)+":"+(min<10?'0':'')+min+":"+(sec<10?'0':'')+sec+(pm ? (hr>12 ? " PM" : " AM") : ""); 
  return time;
}

You can see it in action at https://jsfiddle.net/j2xk312m/3/ using the following code block:

(function() {

  function curTime(pm) {
    var dt = new Date();
    var hr = dt.getHours(), min = dt.getMinutes(), sec = dt.getSeconds();
    var time = (pm ? ((hr+11)%12+1) : (hr<10?'0':'')+hr)+":"+(min<10?'0':'')+min+":"+(sec<10?'0':'')+sec+(pm ? (hr>12 ? " PM" : " AM") : ""); 
    return time;
  }

  alert("12-hour Format:    "+curTime(true)+"\n24-hour Format:    "+curTime(false));

})();

jQuery doesn't have any Date utilities at all. If you don't use any additional libraries, the usual way is to create a JavaScript Date object and then extract the data from it and format it yourself.

For creating the Date object you can either make sure that your date string in the JSON is in a form that Date understands, which is IETF standard (which is basically RFC 822 section 5). So if you have the chance to change your JSON, that would be easiest. (EDIT: Your format may actually work the way it is.)

If you can't change your JSON, then you'll need to parse the string yourself and get day, mouth, year, hours, minutes and seconds as integers and create the Date object with that.

Once you have your Date object you'll need to extract the data you need and format it:

   var myDate = new Date("4 Feb 2011, 19:00:00");
   var hours = myDate.getHours();
   var am = true;
   if (hours > 12) {
      am = false;
      hours -= 12;
   } else (hours == 12) {
      am = false;
   } else (hours == 0) {
      hours = 12;
   }

   var minutes = myDate.getMinutes();
   alert("It is " + hours + " " + (am ? "a.m." : "p.m.") + " and " + minutes + " minutes".);

Please try with below code

var s = "15 Feb 2015 11.30 a.m";
        var times = s.match("((([0-9])|([0-2][0-9])).([0-9][0-9])[\t ]?((a.m|p.m)|(A.M|P.M)))");            
        var time = "";

        if(times != null){                          
            var hour = times[2];
            if((times[6] == "p.m" || times[6] == "P.M")){
                if(hour < 12){
                    hour = parseInt(hour) + parseInt(12);
                }else if(hour == 12){
                    hour = "00";
                }
            }
            time = [hour, times[5], "00"].join(":");

        }

Thanks

I'm a relative newbie, but here's what I came up with for one of my own projects, and it seems to work. There may be simpler ways to do it.

function getTime() {
    var nowTimeDate = new Date();
    var nowHour = nowTimeDate.getHours();
    var nowMinutes = nowTimeDate.getMinutes();
    var suffix = nowHour >= 12 ? "pm" : "am";
    nowHour = (suffix == "pm" & (nowHour > 12 & nowHour < 24)) ? (nowHour - 12) : nowHour;
    nowHour = nowHour == 0 ? 12 : nowHour;
    nowMinutes = nowMinutes < 10 ? "0" + nowMinutes : nowMinutes;
    var currentTime = nowHour + ":" + nowMinutes + suffix;
    document.getElementById("currentTime").innerHTML = currentTime;
}

You could try this more generic function:

function to12HourFormat(date = (new Date)) {
  return {
    hours: ((date.getHours() + 11) % 12 + 1),
    minutes: date.getMinutes(),
    meridian: (date.getHours() >= 12) ? 'PM' : 'AM',
  };
}

Returns a flexible object format.

https://jsbin.com/vexejanovo/edit

date = date.replace(/[0-9]{1,2}(:[0-9]{2}){2}/, function (time) {
    var hms = time.split(':'),
        h = +hms[0],
        suffix = (h < 12) ? 'am' : 'pm';
    hms[0] = h % 12 || 12;        
    return hms.join(':') + suffix
});

edit: I forgot to deal with 12 o'clock am/pm. Fixed.

This worked for me!

function main() {
  var time = readLine();
  var formattedTime = time.replace('AM', ' AM').replace('PM', ' PM');
  var separators = [':', ' M'];
  var hms = formattedTime.split(new RegExp('[' + separators.join('') + ']'));
  if (parseInt(hms[0]) < 12 && hms[3] == 'P')
      hms[0] = parseInt(hms[0]) + 12;
  else if (parseInt(hms[0]) == 12 && hms[3] == 'A')
      hms[0] = '00';
  console.log(hms[0] + ':' + hms[1] + ':' + hms[2]);

}

Here you go

var myDate = new Date("February 04, 2011 19:00:00");
var hr = myDate.getHours(); 
var convHrs = "";
var ampmSwitch = "";
ampmSwitch = (hr > 12)? "PM":"AM"; 
convHrs = (hr >12)? hr-12:hr;
// Build back the Date / time using getMonth/ getFullYear and getDate and other functions on the myDate object. Enclose it inside a func and there you got the working 12 hrs converter ;)

And here's the converter func for yas ;) Happy coding!!

function convertTo12Hrs(yourDateTime){
    var myDate = new Date(yourDateTime);
    var dtObject = new Object();
    var monthsCollection = {0:"January", 1:"February",2:"March",3:"April",4:"May",5:"June",6:"July",7:"August",8:"September",9:"October",10:"November",11:"December"};
    dtObject.year = myDate.getFullYear();
    dtObject.month = monthsCollection[myDate.getMonth()];
    dtObject.day = (myDate.getDate()<10)?"0"+myDate.getDate():myDate.getDate();
    dtObject.minutes = (myDate.getMinutes() < 10)? "0"+myDate.getMinutes():myDate.getMinutes();
    dtObject.seconds = (myDate.getSeconds() < 10)? "0"+myDate.getSeconds():myDate.getSeconds();
    // Check if hours are greater than 12? Its PM
    dtObject.ampmSwitch = (myDate.getHours() > 12)? "PM":"AM";
    // Convert the hours
    dtObject.hour = (myDate.getHours() > 12)?myDate.getHours()-12:myDate.getHours();
    // Add the 0 as prefix if its less than 10
    dtObject.hour = (dtObject.hour < 10)? "0"+dtObject.hour:dtObject.hour;

    // Format back the string as it was or return the dtObject object or however you like. I am returning the object here
    return dtObject;
}

invoke it like convertTo12Hrs("February 04, 2011 19:00:00"); it will return you the object, which in turn you can use to format back your datetime string as you fancy...

this is your html code where you are calling function to convert 24 hour time format to 12 hour with am/pm

<pre id="tests" onClick="tConvert('18:00:00')">_x000D_
  test on click 18:00:00_x000D_
</pre>_x000D_
<span id="rzlt"></span>

now in js code write this tConvert function as it is

 function tConvert (time)_x000D_
  {_x000D_
     _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 > 1) _x000D_
    { // If time format correct_x000D_
        _x000D_
      time = time.slice (1);  // Remove full string match value_x000D_
      time[5] = +time[0] < 12 ? 'AM' : 'PM'; // Set AM/PM_x000D_
      time[0] = +time[0] % 12 || 12; // Adjust hours_x000D_
    }_x000D_
    //return time; // return adjusted time or original string_x000D_
      var tel = document.getElementById ('rzlt');_x000D_
      _x000D_
      tel.innerHTML= time.join ('');_x000D_
  }

converting 18:00:00 to 6:00:00PM working for me

Here is a nice little function that worked for me.

function getDisplayDatetime() {
    var d = new Date(); var hh = d.getHours(); var mm = d.getMinutes(); var dd = "AM"; var h = hh;

    if (mm.toString().length == 1) {
        mm = "0" + mm;
    }

    if (h >= 12) {
        h = hh - 12;
        dd = "PM";
    }

    if (h == 0) {
        h = 12;
    }
    var Datetime = "Datetime: " + d.getFullYear() + "/" + (d.getMonth() + 1) + "/" + d.getUTCDate() + " " + h + ":" + mm;
    return Datetime + " " + dd;
}