正常都是弄个延迟，或者监听 #app 元素变动。。

// 元素变化监听
const fnElChange = (el, fn = () => { }) => {
const observer = new MutationObserver((mutationRecord, mutationObserver) => {
// _log('body attributes changed!!!'); // body attributes changed!!!
// _log('mutationRecord = ', mutationRecord); // [MutationRecord]
// _log('mutationObserver === observer', mutationObserver === observer); // true
fn(mutationRecord, mutationObserver);
// mutationObserver.disconnect();
});
observer.observe(el, {
// attributes: false,
// attributeFilter: ["class"],
childList: true,
// characterData: false,
subtree: true,
});
}