javascript detect when number of elements change
const targetNode = document.body;
const config = { childList: true, subtree: true };
const callback = function(mutationsList, observer) {
for(let mutation of mutationsList) {
if (mutation.type === 'childList') {
// Elements have changed
}
}
};
const observer = new MutationObserver(callback);
observer.observe(targetNode, config);