XPath error The document has mutated since the result was returned

Question

I'm trying to use xpath on a page but am getting the error Uncaught DOMException: Failed to execute 'iterateNext' on 'XPathResult': The document has mutated since the result was returned.

xpath = document.evalutate('//a', document)
xpath.iterateNext()

What's wrong?

Answer 1

The problem was that the page is mutated between the time the XPathResult object is generated and the time when you access an object in it.

Instead use snapshots

xpath = document.evaluate('//td/a', document, null, XPathResult.ORDERED_NODE_SNAPSHOT_TYPE, null)
xpath.snapshotItem(0)
xpath.snapshotItem(1)

Answer 2

If your propose is read only, it's possible to clone the context node:

xpath = document.evaluate('//a', document.cloneNode(true))
xpath.iterateNext()