# Example 開發中的 [webedtior](https://app.stoneapp.tech/editor) 的一段 code ```javascript let observer = new MutationObserver((mutation, observer) => { parent.postMessage({ "status": "titleUpdate", "title": (document.title || "No title") }, "*"); }); observer.observe(document.querySelector('title'),{ childList: true, subtree: true }); ``` reference: - https://stackoverflow.com/questions/2497200/how-to-listen-for-changes-to-the-title-element - https://developer.mozilla.org/en-US/docs/Web/API/MutationObserver