script.js

const spinner = document.createElement("div");
spinner.classList.add("spinner");

["ball-1", "ball-2", "ball-3", "ball-4"].forEach(ballNumber => {
  const ball = document.createElement("div");
  ball.classList.add("ball");
  ball.classList.add(ballNumber);
  spinner.appendChild(ball);
});

document.body.appendChild(spinner);