This tests accessing the length after accessing (length + 1)-th item in HTMLCollection doesn't cache a wrong length. On success, you will see a series of "PASS" messages, followed by "TEST COMPLETE". PASS children = container.children; children.length is 0 PASS container.appendChild(span); children[1]; children.length is 1 PASS container.removeChild(span); children.length is 0 PASS successfullyParsed is true TEST COMPLETE