This tests that the querySelector and querySelectorAll fast path for IDs is not overzelous. On success, you will see a series of "PASS" messages, followed by "TEST COMPLETE". PASS document.querySelector('#testId') is correctNode PASS document.querySelector('div#testId') is correctNode PASS document.querySelector('ul#testId') is null PASS document.querySelector('ul #testId') is null PASS document.querySelector('#testId[attr]') is null PASS document.querySelector('#testId:not(div)') is null PASS document.querySelectorAll('div#testId').length is 1 PASS document.querySelectorAll('div#testId').item(0) is correctNode PASS document.querySelectorAll('#testId').length is 1 PASS document.querySelectorAll('#testId').item(0) is correctNode PASS document.querySelectorAll('ul#testId').length is 0 PASS document.querySelectorAll('ul #testId').length is 0 PASS document.querySelectorAll('#testId[attr]').length is 0 PASS document.querySelectorAll('#testId:not(div)').length is 0 PASS successfullyParsed is true TEST COMPLETE