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Add two string time values (HH:mm:ss) with javascript
/**
* Add two string time values (HH:mm:ss) with javascript
*
* Usage:
* > addTimes('04:20:10', '21:15:10');
* > "25:35:20"
* > addTimes('04:35:10', '21:35:10');
* > "26:10:20"
* > addTimes('30:59', '17:10');
* > "48:09:00"
* > addTimes('19:30:00', '00:30:00');
* > "20:00:00"
*
* @param {String} startTime String time format
* @param {String} endTime String time format
* @returns {String}
*/
function addTimes (startTime, endTime) {
var times = [ 0, 0, 0 ]
var max = times.length
var a = (startTime || '').split(':')
var b = (endTime || '').split(':')
// normalize time values
for (var i = 0; i < max; i++) {
a[i] = isNaN(parseInt(a[i])) ? 0 : parseInt(a[i])
b[i] = isNaN(parseInt(b[i])) ? 0 : parseInt(b[i])
}
// store time values
for (var i = 0; i < max; i++) {
times[i] = a[i] + b[i]
}
var hours = times[0]
var minutes = times[1]
var seconds = times[2]
if (seconds >= 60) {
var m = (seconds / 60) << 0
minutes += m
seconds -= 60 * m
}
if (minutes >= 60) {
var h = (minutes / 60) << 0
hours += h
minutes -= 60 * h
}
return ('0' + hours).slice(-2) + ':' + ('0' + minutes).slice(-2) + ':' + ('0' + seconds).slice(-2)
}
@joseluisq
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joseluisq commented Jan 8, 2018

@AjeshM thanks!

@Gelenkesteffen
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Gelenkesteffen commented Jan 19, 2018

Hi, for my use case I needed to add support for 24hour calculation so for instance 11:55 + 14:00 = 01:55. Therfore I added the foolowing statement:

if(hours >= 24){
hours = hours %24;
hours = hours < 0 ? 24 + hours : +hours;
}

@joseluisq
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joseluisq commented Feb 12, 2018

I have published https://github.com/joseluisq/timelite
Feedback welcome!

@TZNaso
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TZNaso commented Jan 10, 2019

There is a problem when sum more than 99 hours. You can fix just change to -3 (or how many fields you will use, example: if 1000+ hours, you should use -4) in this line: return ('0' + hours).slice(-2) + ':' + ('0' + minutes).slice(-2) + ':' + ('0' + seconds).slice(-2)

@myas92
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myas92 commented Dec 26, 2019

I think for this return ('0' + hours).slice(-2) + ':' + ('0' + minutes).slice(-2) + ':' + ('0' + seconds).slice(-2) you should write this :
hours = (hours < 10) ? 0${hours} : hours
minutes = (minutes < 10) ? 0${minutes} : minutes
seconds = (seconds < 10) ? 0${seconds} : seconds
return ${hours}:${minutes}:${seconds}

because for sum more than 99 hours, result is incorrect

@ganmor
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ganmor commented Aug 1, 2020

You are missing radis parameter in parse int

If radix is undefined or 0 (or absent), JavaScript assumes the following: If the input string begins with "0x" or "0X", radix is 16 (hexadecimal) and the remainder of the string is parsed. If the input string begins with "0", radix is eight (octal) or 10 (decimal).

@vanpariyar
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vanpariyar commented Jan 7, 2021

Just implement your code in this tools https://vanpariyar.github.io/useful-tools

Thank you so much ...

@olmos31
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olmos31 commented Apr 16, 2021

Thank you!

@trynx
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trynx commented Dec 27, 2021

If there is a need for longer hours, not only 2 digits like in my case, you can change in the return of the hours from split(-2) to split(-3)

return ('0' + hours).slice(-3) + ':' + ('0' + minutes).slice(-2) + ':' + ('0' + seconds).slice(-2)

@grauziitisos
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grauziitisos commented Apr 6, 2022

Actually some company out there thinks the opposite
( regarding what is the meaning of shorter form ).

from opensource projects I can name ffmpeg, for example.

that shorter form means there are only the smaller units not the bigger ones :-D

So to turn that mode on here:
//4 lines:
//beggining:

function addTimes (startTime, endTime, shortMeansSmaller) {
	var s = shortMeansSmaller;

// and then line 8 as is (i cite here it as first line)

//8th line:
  var b = (endTime || '').split(':')
  if(s) { if(a.length <3){var l = a.length; var t=[]; for(var i=0; i<l; i++) t.push(a.pop()); for(var i=0; i<3-l; i++) a.push(0); for(var i=0; i<l; i++) a.push(t.pop());}
  if(b.length <3){var l = b.length; var t=[]; for(var i=0; i<l; i++) t.push(b.pop()); for(var i=0; i<3-l; i++) b.push(0); for(var i=0; i<l; i++) b.push(t.pop()); }
  }

Then with the data:

var tm = ['13:22', '56:19', '1:22:13', '47:19', '24:49', '26:55', '1:09:02', '43:38', '17:53', '1:08:45', '52:44', '32:41', '55:25'];

This

var tn = []; for(var t =0; t<tm.length-1; t+=2){ tn.push(addTimes(tm[t], tn[t+1]));
if(tm.length/2>tn.length) tn.push(tm[tm.length-1]);
//tn:
//['69:41:00', '48:41:13', '51:44:00', '44:47:02', '19:01:45', '85:25:00', '55:25']

Turns into this:

var tn = []; for(var t =0; t<tm.length-1; t+=2) tn.push(addTimes(tm[t], tm[t+1], 1));
if(tm.length/2>tn.length) tn.push(tm[tm.length-1]);
//tn
// ['01:09:41', '02:09:32', '00:51:44', '01:52:40', '01:26:38', '01:25:25', '55:25']

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