function throttle(fn, wait = 100) {
  let last = 0;
  let timer;
  return (...args) => {
    const now = Date.now();
    const remaining = wait - (now - last);
    clearTimeout(timer);
    if (remaining <= 0) {
      last = now;
      fn(...args);
    } else {
      timer = setTimeout(() => { last = Date.now(); fn(...args); }, remaining);
    }
  };
}