JSFiddle - React, Tailwind, and code Playground

HTML

<div class="formSubmitButton">
    <input type="submit" value="Submit">
</div>

JavaScript

// select the target node
var target = document.querySelector('div.formSubmitButton input[type="submit"]');
 
// create an observer instance
var observer = new MutationObserver(function(mutations) {
    mutations.forEach(function(mutation) {
        console.log(mutation);
    });    
});
 
// 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);


// Triggering a change with JS on the target
target.style.color = 'red'