What's a simple way to convert between an am/pm time to 24 hour time in javascript

Question

I\'ve been playing with jquery and I\'ve run myself into a time problem. I\'ve got 3 time input select boxes, one for hours, one for minutes, and one for the Meridian. I need to

Answer 1

Just to add a plain JS answer, the following will format the time based on the length of the initial string. If h:mm returns HH:mm, if h:mm:ss returns HH:mm:ss.

If HH:mm:ss is always required, it's simple to add default seconds of ":00" if not present in initial string.

// Change time in h:mm:ss ap to  HH:mm:ss time
// If time missing seconds, returns HH:mm
function timeToHHmm(time) {
  var nums = time.match(/\d+/g);
  var am   = /am/i.test(time);
  nums[0] = ('0' + ((nums[0]%12) + (am? 0 : 12))).slice(-2);
  // If HH:mm:ss required, use following line instead of last
  // return nums.join(':') + (nums.length == 2? ':00' : '');
  return nums.join(':');
}

// Some tests
['2:45am',     // hh:mm only
 '5:15:45pm',  // hh:mm:ss
 '5:15:45 pm', // space before am/pm
 '05:15:45 pm',// leading zero on hour
 '12:02am',
 '12:02 pm',
 '12:02:00am'
 ].forEach(function(time) {
  console.log(time + ' => ' + timeToHHmm(time));
});