Undo programmatically added stuff
Type something, then click + stuff. Then try to undo (Ctrl+Z).
HTML
<input id="targetText" type="text" placeholder="type something" />
<input id="enterText" type="button" value="+ stuff" />
JavaScript
const inputText = window.targetText;
const button = window.enterText;
button.addEventListener('click', () => {
inputText.value += ', stuff';
inputText.focus();
});