Calculate Time Difference with JavaScript

Question

I have two HTML input boxes, that need to calculate the time difference in JavaScript onBlur (since I need it in real time) and insert the result to new input box.

F

Answer 1

Depending on what you allow to enter, this one will work. There may be some boundary issues if you want to allow 1am to 1pm

NOTE: This is NOT using a date objects or moment.js

function pad(num) {
  return ("0"+num).slice(-2);
}
function diffTime(start,end) {
  var s = start.split(":"), sMin = +s[1] + s[0]*60,
      e =   end.split(":"), eMin = +e[1] + e[0]*60,
   diff = eMin-sMin;
  if (diff<0) { sMin-=12*60;  diff = eMin-sMin }
  var h = Math.floor(diff / 60),
      m = diff % 60;
  return "" + pad(h) + ":" + pad(m);
}  
document.getElementById('button').onclick=function() {
  document.getElementById('delay').value=diffTime(
      document.getElementById('timeOfCall').value, 
      document.getElementById('timeOfResponse').value
  );
}

CLICK