function tConvert (time) {
// Check correct time format and split into components
time = time.toString ().match (/^([01]d|2[0-3])(:)([0-5]d)(:[0-5]d)?$/) || [time];
if (time.length > 1) { // If time format correct
time = time.slice (1); // Remove full string match value
time[5] = +time[0] < 12 ? 'AM' : 'PM'; // Set AM/PM
time[0] = +time[0] % 12 || 12; // Adjust hours
}
return time.join (''); // return adjusted time or original string
}
tConvert ('18:00:00');