Simple clock logic for an analogue clock on your screen.

clock.js

// Link to code pen https://codepen.io/jaspercreel/pen/QMOepX

const secHand = document.getElementById('secHand');

const minHand = document.getElementById('minHand');

const hourHand = document.getElementById('hourHand');

const start = -90;
  
const date = new Date();
let seconds = date.getSeconds();
let minutes = date.getMinutes();
let hours = date.getHours();

const rotate = () => {
  seconds++;
  
  if (seconds === 60) {
    seconds = 0;
    minutes++;
  }
  
  if (minutes === 60) {
    minutes = 0;
    hours++;
  }
  
  if (hours === 12) {
    hours = 0;
  }
  
  const secRotate = ((360/60) * seconds) + start;
  
  const minRotate = ((360/60) * minutes) + start;
  
  const hourRotate = ((360/12) * hours) + start;
  
  secHand.setAttribute('style', 'transform: rotate(' + secRotate + 'deg)');
  
  minHand.setAttribute('style', 'transform: rotate(' + minRotate + 'deg)');
  
  hourHand.setAttribute('style', 'transform: rotate(' + hourRotate + 'deg)');
  
}

setInterval(rotate, 1000);