function diff(start, end) {
start = start.split(":");
end = end.split(":");
var startDate = new Date(0, 0, 0, start[0], start[1], 0);
var endDate = new Date(0, 0, 0, end[0], end[1], 0);
var diff = endDate.getTime() - startDate.getTime();
var hours = Math.floor(diff / 1000 / 60 / 60);
diff -= hours * 1000 * 60 * 60;
var minutes = Math.floor(diff / 1000 / 60);
// If using time pickers with 24 hours format, add the below line get exact hours
if (hours < 0)
hours = hours + 24;
return (hours <= 9 ? "0" : "") + hours + ":" + (minutes <= 9 ? "0" : "") + minutes;
}