Lowest Hiding Element

Requirements

• Export lowestHidingElement(elements) as named and default. Accept an array of Element references and return their deepest common containing Element, or null when none exists.
• Containment includes the element itself. A single element returns itself; repeated references do not change the result. When one input contains all others, return that input.
• An empty array returns null. Detached elements in the same subtree are supported. Elements in unrelated detached trees or different documents return null.
• Use ordinary parentElement relationships. Do not cross document fragments or shadow-root boundaries. Shadow DOM composed-tree behavior is outside scope.
• Only find and return the element. Do not hide elements, change attributes/styles, reorder nodes, or mutate the input array.

Examples

Input: lowestHidingElement([firstButton, secondButton])
Output: The deepest shared containing element, such as their toolbar.

Input: lowestHidingElement([element])
Output: element