JSFiddle - React, Tailwind, and code Playground

HTML

<input type="checkbox" id="testCheckbox">
<input type="button" onclick="var cb = document.getElementById('testCheckbox'); cb.checked = !cb.checked" value="Toggle checkbox">

JavaScript

document.getElementById("testCheckbox").onpropertychange = function(evt) {
    evt = evt || window.event;
    if (evt.propertyName == "checked") {
        alert("Checkedness changed!");
    }
};