dom元素改变监听
function domChange(domId, callback) { // select the target node var target = document.getElementById(domId); // create an observer instance var observer = new MutationObserver(function (mutations) { mutations.forEach(function (mutation) { callback(); }); }); // configuration of the observer: var config = { attributes: true, childList: true, characterData: true }; // pass in the target node, as well as the observer options observer.observe(target, config); // later, you can stop observing //observer.disconnect(); }