This test passes if the nth-of-type can accept a parameter that is an+b, odd or even. But it does not accept any other parameter. On success, you will see a series of "PASS" messages, followed by "TEST COMPLETE". debug("These spans should alternate red and green"); span span span span span span span span debug("These spans should alternate red and green"); span span span span span span span span debug("These spans should be black"); span span span span span span span span debug("These spans should be black"); span span span span span span span span PASS document.defaultView.getComputedStyle(el, null).getPropertyValue('color') is 'rgb(255, 0, 0)' PASS document.defaultView.getComputedStyle(el, null).getPropertyValue('color') is 'rgb(0, 128, 0)' PASS document.defaultView.getComputedStyle(el, null).getPropertyValue('color') is 'rgb(255, 0, 0)' PASS document.defaultView.getComputedStyle(el, null).getPropertyValue('color') is 'rgb(0, 128, 0)' PASS document.querySelector("span.c3:nth-of-type(n3)") threw exception Error: SYNTAX_ERR: DOM Exception 12. PASS document.querySelector("span.c3:nth-of-type(foo)") threw exception Error: SYNTAX_ERR: DOM Exception 12. PASS document.querySelector("span.c3:nth-of-type(2n3)") threw exception Error: SYNTAX_ERR: DOM Exception 12. PASS document.querySelector("span.c3:nth-of-type(foon + bar)") threw exception Error: SYNTAX_ERR: DOM Exception 12. PASS successfullyParsed is true TEST COMPLETE