JSFiddle - React, Tailwind, and code Playground
HTML
<form id="form">
<input type="hidden" name="id" />
</form>
Result of using .id:
<div id="result">
</div>
<br>
Result of using getAttribute:
<div id="getAttributeResult">
</div>
JavaScript
element = document.getElementById('form');
document.getElementById('result').innerHTML = element.id
document.getElementById('getAttributeResult').innerHTML = element.getAttribute('id')