[TS: Browser Only Function] Executes fn arg only if window is in global #typescript #browser

browserOnly.ts

/**
 * Safely execute browser only code.
 *
 * @param fn - The function to execute.
 * @param fallback - Optional default return value.
 *
 */
function browserOnly<T>(
  fn: (window: Window, document: Document) => T,
  fallback?: T
): T | undefined {
  if (!window || !document) {
    return fallback;
  }

  return fn(window, document);
}