如何检测从 dom 元素中添加/删除的元素？

Question

Say I had a div#parent and I append and remove elements to it using jquery. How would I be able to detect when such an event happens on the div#parent element?

Answer 1

Don't use mutation events like DOMNodeInserted and DOMNodeRemoved.

Instead, use DOM Mutation Observers , which are supported in all modern browsers except IE10 and lower ( Can I use ). Mutation observers are intended to replace mutation events (which have been deprecated), as they have been found to have low performance due to flaws in its design .

var x = new MutationObserver(function (e) {
  if (e[0].removedNodes) console.log(1);
});

x.observe(document.getElementById('parent'), { childList: true });

Answer 2

Use Mutation Observers as suggested by @Qantas in his answer

---

Following methods are deprecated

You can use DOMNodeInserted and DOMNodeRemoved

$("#parent").on('DOMNodeInserted', function(e) {
    console.log(e.target, ' was inserted');
});

$("#parent").on('DOMNodeRemoved', function(e) {
    console.log(e.target, ' was removed');
});

MDN Docs

Answer 3

You should bind DOMSubtreeModified event

$("#parent").bind("DOMSubtreeModified",function(){
  console.log('changed');
});

http://jsfiddle.net/WQeM3/

Answer 4

It wouldn't let me comment below on the top answer but to answer your question @DenisKolodin, in order to listen for self-destruction, you can do something like this:

function watchElForDeletion(elToWatch, callback, parent = document.querySelector('body')){
  const observer = new MutationObserver(function (mutations) {

    // loop through all mutations
    mutations.forEach(function (mutation) {

        // check for changes to the child list
        if (mutation.type === 'childList') {

            // check if anything was removed and if the specific element we were looking for was removed
            if (mutation.removedNodes.length > 0 && mutation.removedNodes[0] === elToWatch) {
                callback();
            }
        }
    });
  });

  // start observing the parent - defaults to document body
  observer.observe(parent, { childList: true });
};

It defaults to the parent being the body element and only runs the callback if the specific element you're looking for is deleted.

Answer 5

I think we use socket.io..

because of we detect which element should be added and then possibly to guess which element will be removed

Maybe it's possible

Thanks