The read-only invalidIteratorState property of the XPathResult interface signifies that the iterator has become invalid. It is true if XPathResult.resultType is UNORDERED_NODE_ITERATOR_TYPE or ORDERED_NODE_ITERATOR_TYPE and the document has been modified since this result was returned. 
 
A boolean value indicating whether the iterator has become invalid.
 
The following example shows the use of the invalidIteratorState property.
 
<div>XPath example</div>
<p>Iterator state: <output></output></p>
  
const xpath = "//div";
const result = document.evaluate(
  xpath,
  document,
  null,
  XPathResult.ANY_TYPE,
  null,
);
document.querySelector("div").remove();
document.querySelector("output").textContent = result.invalidIteratorState
  ? "invalid"
  : "valid";