Trigger JS After An Element Has Changed. MutationObserver

You can use the MutationObserver API to observe changes to the DOM and trigger a function when a specific element is added to the DOM. Here’s an example of how to use MutationObserver:

// Select the node that will be observed for mutations
const targetNode = document.getElementById('my-element');

// Options for the observer (which mutations to observe)
const config = { attributes: true, childList: true, subtree: true };

// Callback function to execute when mutations are observed
const callback = function(mutationsList, observer) {
    for(let mutation of mutationsList) {
        if (mutation.type === 'childList' && mutation.addedNodes.length > 0) {
            const addedNode = mutation.addedNodes[0];
            if ( === 'my-element') {
                // Do something with myElement

// Create an observer instance linked to the callback function
const observer = new MutationObserver(callback);

// Start observing the target node for configured mutations
observer.observe(targetNode, config);

In this example, we first select the node we want to observe for mutations (targetNode). We then define the options for the observer (config) and the callback function that will be executed when mutations are observed (callback).

The callback function checks for mutations of type childList (i.e. the addition or removal of a child node) and if a node is added, it checks if the added node has the id my-element. If it does, we can then do something with that element.

Finally, we create an instance of the MutationObserver class and start observing the target node for mutations using the observe() method.

Here’s a good video on MutationObserver by Web Dev Simplified -> (1) This Is Unbelievably Powerful – YouTube

Blinky the fish animated gif