The NodeIterator.pointerBeforeReferenceNode read-only property returns a boolean flag that indicates whether the NodeFilter is anchored before (if this value is true) or after (if this value is false) the anchor node indicated by the NodeIterator.referenceNode property.
A boolean.
const nodeIterator = document.createNodeIterator(
document.body,
NodeFilter.SHOW_ELEMENT,
{
acceptNode(node) {
return NodeFilter.FILTER_ACCEPT;
},
},
);
flag = nodeIterator.pointerBeforeReferenceNode;NodeIterator