Fix : ReferenceError: window is not defined in JavaScript

main.js

if (typeof window !== 'undefined') {
  console.log('You are on the browser');

  // ✅ Can use window here
  console.log(window.innerWidth);

  window.addEventListener('mousemove', () => {
    console.log('Mouse moved');
  });
} else {
  console.log('You are on the server');
  // ⛔️ Don't use window here
}