CODE EXAMPLE FOR JAVASCRIPT

12 hours to 24 hours javascript

var time = $("#starttime").val();
var hours = Number(time.match(/^(d+)/)[1]);
var minutes = Number(time.match(/:(d+)/)[1]);
var AMPM = time.match(/s(.*)$/)[1];
if(AMPM == "PM" && hours<12) hours = hours+12;
if(AMPM == "AM" && hours==12) hours = hours-12;
var sHours = hours.toString();
var sMinutes = minutes.toString();
if(hours<10) sHours = "0" + sHours;
if(minutes<10) sMinutes = "0" + sMinutes;
alert(sHours + ":" + sMinutes);