Number of hours to HH:MM with Moment.js (or without)

Question

I have very simple problem, but couldn't find good simple DRY solution. I want to convert number of hours to HH:MM format. My try with Moment.js is:

var hours = 10.5
var hour_string = moment(hours*3600*1000).format('HH:MM')

But unfortunately I get:

"11:01"

and have no idea why. Of course my wanted result is "10:30".

I'd like just do it in the easiest way, similar as I can do in Rails:

Time.at(hours*3600).utc.strftime("%H:%M")

Any ideas?

Validate

Answer 1

Okay, I found the reason. "MM" means months, not minutes, which are "mm". And the hour shift was caused by timezones, which we can omit using the utc function. The final solution is:

moment.utc(hours*3600*1000).format('HH:mm')

Validate

Please note that this fails for numbers over 24 as moment then refers to this value as 1 day. e.g. moment.utc(24*3600*1000).format('HH:mm') => '00:00' – Logorrhea

Answer 2

let hour = 10;
let minute = 30;

moment({ hour, minute }).format('HH:mm');

// output: 10:30

Dale

This doesn't account for the time zone issue and ignores the fact that OP is using a float for hours, not hours and minutes. – Lexicostatistics