This tests that the querySelector, querySelectorAll and matchesSelector (webkitMatchesSelector) correctly stringify null and undefined to "null" and "undefined". On success, you will see a series of "PASS" messages, followed by "TEST COMPLETE". PASS document.querySelector(null) is nullNode PASS document.querySelector(undefined) is undefinedNode PASS document.querySelectorAll(null).length is 1 PASS document.querySelectorAll(null).item(0) is nullNode PASS document.querySelectorAll(undefined).length is 1 PASS document.querySelectorAll(undefined).item(0) is undefinedNode PASS nullNode.webkitMatchesSelector(null) is true PASS undefinedNode.webkitMatchesSelector(undefined) is true PASS successfullyParsed is true TEST COMPLETE