Node.firstChild & Node.lastChild
Get the first and last child nodes of a parent element, including nodes that aren’t elements (such as comments and text fragments).
<ul>
<!-- The gray wizard -->
<li>Gandalf</li>
<li>Radagast</li>
<li>Hermione</li>
<!-- The surprise hero -->
<li>Neville</li>
</ul>
let wizards = document.querySelector('ul');
// returns the comment node <!-- The gray wizard -->
let firstDescendant = wizards.firstChild;
// returns <li>Neville</li>
let lastDescendant = wizards.lastChild;