var inputEle = document.getElementById('timeInput'); function onTimeChange() { var timeSplit = inputEle.value.split(':'), hours, minutes, meridian; hours = timeSplit[0]; minutes = timeSplit[1]; if (hours > 12) { meridian = 'PM'; hours -= 12; } else if (hours < 12) { meridian = 'AM'; if (hours == 0) { hours = 12; } } else { meridian = 'PM'; } alert(hours + ':' + minutes + ' ' + meridian); }