• JS

const d = new Date();

let hr = d.getHours();
let min = d.getMinutes();
let sec = d.getSeconds();

if ( hr.toString().length === 1 ) {
  hr = '0' + hr;
}

if ( min.toString().length === 1 ) {
  min = '0' + min;
}

if ( sec.toString().length === 1 ) {
  sec = '0' + sec;
}

const x = '' + hr + ':' + min + ':' + sec;

• JS

let f = new Intl.DateTimeFormat(undefined, {
    hour: '2-digit',
    minute: '2-digit',
    second: '2-digit',
    hourCycle: 'h24'
}), x = f.format(d)

• Ada

X : constant String :=
    Ada.Calendar.Formatting.Image (D) (12 .. 19);

• C#

var x = date.ToString("HH:mm:ss");

• Fortran

integer, dimension(8) :: d
character (len=8) :: x
call date_and_time (values=d)
write (unit=x,fmt='(I2.2,":",I2.2,":",I2.2)') d(5), d(6), d(7)

• Go

x := d.Format("15:04:05")

• Java

Date d = getInstance().getTime();
String x = "%tT".formatted(d);

• Java

long d = currentTimeMillis();
String x = "%tH:%<tM:%<tS".formatted(d);

• Lisp

(defvar *x* (format NIL "~2,'0D:~2,'0D:~2,'0D" 12 34 56))

• PHP

$x = $d->format('H:i:s');

• Pascal

DefaultFormatSettings.TimeSeparator := ':';
DefaultFormatSettings.ShortTimeFormat := 'hh:mm:ss';
x := TimeToStr(d);

• Perl

$d = DateTime->now; 
$x = $d->hms;

• Python

d = datetime.datetime.now()
x = d.strftime('%H:%M:%S')

• Python

d = datetime.now()
x = d.time().isoformat('seconds')

• Ruby

d = Time.now
x = d.strftime("%H:%M:%S")

• Rust

let format = format_description!("[hour]:[minute]:[second]");
let x = d.format(&format).expect("Failed to format the time");

• Scheme

(define d (current-date))
(define x (substring (date-and-time d) 11 19))