wait-for-element.ts

export function watchForElement<T extends Element = Element>(
  selector: string,
  callback: (element: T, observer: MutationObserver) => void,
  options: MutationObserverInit = { childList: true },
  targetNode = document.body,
) {
  const observer = new MutationObserver((mutationsList) => {
    for (const mutation of mutationsList) {
      if (mutation.type === 'childList') {
        const element = document.querySelector<T>(selector);
        if (element) {
          callback(element, observer);
          return;
        }
      }
    }
  });

  observer.observe(targetNode, options);

  return observer;
}