HTMLify

document.querySelector("body").addEventListener("mousemove", eyeball);

function eyeball() {
  let eyes = document.querySelectorAll(".eye");
  eyes.forEach((eye) => {
    let x = eye.getBoundingClientRect().left + eye.clientWidth / 2;
    let y = eye.getBoundingClientRect().top + eye.clientHeight / 2;

    let radian = Math.atan2(event.pageX - x, event.pageY - y);
    let rotate = radian * (180 / Math.PI) * -1 + 270;
    eye.style.transform = `rotate(${rotate}deg)`;
  });
}