isEmpty(node, ignoreFn) {
			for (let child = node?.firstElementChild; child != null; child = child.nextElementSibling)
				if (!child.classList.contains('hidden') && !ignoreFn?.(child))
					return false;

			return true;
		}
Tests whether a given DOM `Node` instance is empty or appears
empty.

Any element child nodes which have the CSS class `hidden` set
or for which the optionally passed `ignoreFn` callback function
returns `false` are ignored.

@instance
@memberof LuCI.dom
@param {Node} node
The DOM `Node` instance to test.

@param {LuCI.dom~ignoreCallbackFn} [ignoreFn]
Specifies an optional function which is invoked for each child
node to decide whether the child node should be ignored or not.

@returns {boolean}
Returns `true` if the node does not have any children or if
any children node either has a `hidden` CSS class or a `false`
result when testing it using the given `ignoreFn`.