How to convert decimal hour value to hh:mm:ss

Question

How can I convert a decimal hour value like 1.6578 to hh:mm:ss in jquery or javascript?

I only managed to do it to hh:mm using this code:

var decimaltime= "1.6578";
var hrs = parseInt(Number(decimaltime));
var min = Math.round((Number(decimaltime)-hrs) * 60);
var clocktime = hrs+':'+min;

Answer 1

Rather than doing the calculations yourself, use built-in functionality to set the seconds on an arbitrary date of a Date object, convert it to a string, and chop off the date part, leaving just the hh:mm:ss string.

var decimalTimeString = "1.6578";
var n = new Date(0,0);
n.setSeconds(+decimalTimeString * 60 * 60);
document.write(n.toTimeString().slice(0, 8));

Answer 2

You could do something like this:

var decimalTimeString = "1.6578";
var decimalTime = parseFloat(decimalTimeString);
decimalTime = decimalTime * 60 * 60;
var hours = Math.floor((decimalTime / (60 * 60)));
decimalTime = decimalTime - (hours * 60 * 60);
var minutes = Math.floor((decimalTime / 60));
decimalTime = decimalTime - (minutes * 60);
var seconds = Math.round(decimalTime);
if(hours < 10)
{
 hours = "0" + hours;
}
if(minutes < 10)
{
 minutes = "0" + minutes;
}
if(seconds < 10)
{
 seconds = "0" + seconds;
}
alert("" + hours + ":" + minutes + ":" + seconds);

Answer 3

I found this function worked very well in converting my decimal value of seconds into a standard time string of hh:mm:ss

function formatDuration(seconds) {
  return new Date(seconds * 1000).toISOString().substring(11, 11 + 8);
}
const secondsInDecimal = 1.6578;
formatDuration(secondsInDecimal);

// "00:00:01"

References:

• Date constructor
• toISOString
• substring()

Process:

1. new Date(seconds * 1000) returns this string "Wed Dec 31 1969 19:00:01 GMT-0500 (Eastern Standard Time)"
2. toISOString() is a method on the Date object that changes the returned string into, "1970-01-01T00:00:01.657Z". This is a simplified string returned from #1 above.
3. Running substring() on that string returns a portion of it, from the 11th index, out for a length of 8 more indexes (indices). That value is, "00:00:01".

Answer 4

I realize this is not exactly what the original poster needed, but I needed to get days, hours, and minutes from a decimal time that I could then use for calculations and setting a date object. Many other posts are using outdated methods involving strings and slicing, etc.

const decimalHours = 27.33;
const n = new Date(0,0);
n.setMinutes(+Math.round(decimalHours * 60)); 
const days = (n.getDate() - 1)
const hours = n.getHours()
const minutes = n.getMinutes()
console.log("Days: ",days, "Hours: ",hours, "Minutes: ",minutes)

const decimalHours = 4.33;
const n = new Date(0,0);
n.setMinutes(+Math.round(decimalHours * 60)); 
const days = (n.getDate() - 1)
const hours = n.getHours()
const minutes = n.getMinutes()
console.log("Days: ",days, "Hours: ",hours, "Minutes: ",minutes)

Note that this is not designed for hour values over a month long.

Answer 5

This is working for my purpose

function formatHoursMinutesSeconds(num){
  var hours = Math.floor(num * 24);
  var minutes = Math.floor(((num * 24) - hours) * 60);
  var seconds = Math.floor(((((num * 24) - hours) * 60)-minutes)*60);

  return (hours + ":" + minutes.toString().padStart(2, '0') + ":" + 
  seconds.toString().padStart(2, '0'));
 }