The Node.lastChild read-only property returns the last child of the node. If its parent is an element, then the child is generally an element node, a text node, or a comment node. It returns null if there are no child elements.
The Node.previousSibling read-only property returns the node immediately preceding the specified one in its parent's childNodes list, or null if the specified node is the first in that list.
The NodeIterator.whatToShow read-only property represents an unsigned integer representing a bitmask signifying what types of nodes should be returned by the NodeIterator.
The NonDocumentTypeChildNode.nextElementSibling read-only property returns the element immediately following the specified one in its parent's children list, or null if the specified element is the last one in the list.