Debounce a function

/**
 * Returns a debounced version of `fn` that delays invocation
 * until `wait` ms have passed since the last call.
 */
export function debounce(fn, wait = 200) {
  let timer;

  function debounced(...args) {
    clearTimeout(timer);
    timer = setTimeout(() => {
      timer = undefined;
      fn.apply(this, args);
    }, wait);
  }

  debounced.cancel = () => {
    clearTimeout(timer);
    timer = undefined;
  };

  return debounced;
}