In addition to the testing for previous siblings, ":nth-child(An+B of selectorList)" must also test there is a parent element.

On success, you will see a series of "PASS" messages, followed by "TEST COMPLETE".


PASS getComputedStyle(document.querySelector("html")).backgroundColor is "rgb(255, 255, 255)"
PASS document.querySelector("html:nth-child(n of *), html:nth-child(n of :not(notThere)), html:nth-child(odd of *), html:nth-child(odd of :not(notThere)), html:nth-child(even of *), html:nth-child(even of :not(notThere))") is null
#test-tree initially match when it is attached to the document
PASS document.querySelector("#test-tree:nth-child(n of *)") is document.getElementById("test-tree")
PASS testTree.matches("#test-tree:nth-child(n of *)") is true
After detaching #test-tree, :nth-child() no longer matches because it does not have a parent element.
PASS document.querySelector("#test-tree:nth-child(n of *)") is null
PASS testTree.matches("#test-tree:nth-child(n of *)") is false
PASS testTree.matches("#test-tree") is true
PASS successfullyParsed is true

TEST COMPLETE