This adapter works like the DOM Level 3 method property.
Snapshots do not change with document mutations, so unlike the iterators the snapshot does not become invalid, but it may not correspond to the current document, for example the nodes may have been moved, it might contain nodes that no longer exist, or new nodes could have been added. Note that, for the unordered subtype the single node returned might not be the first in document order, but for the ordered subtype you are guaranteed to get the first matched node in the document order.
The main interface to using XPath is the evaluate function of the document object.
This method evaluates XPath expressions against an XML based document (including HTML documents), and returns a object, which can be a single node or a set of nodes.
The existing documentation for this method is located at document.evaluate, but it is rather sparse for our needs at the moment; a more comprehensive examination will be given below. Note: XPath defines QNames without a prefix to match only elements in the null namespace.