This test checks the style invalidation does not dirty elements that cannot be affected by the changes. On success, you will see a series of "PASS" messages, followed by "TEST COMPLETE". Initially, we should have a match. After getting the style, nothing should require a style recalc. PASS getComputedStyle(document.querySelectorAll(".test-case, .test-case :not(target)")[0]).backgroundColor is "rgb(255, 254, 253)" PASS getComputedStyle(document.querySelectorAll(".test-case, .test-case :not(target)")[1]).backgroundColor is "rgb(255, 254, 253)" PASS getComputedStyle(document.querySelectorAll(".test-case, .test-case :not(target)")[2]).backgroundColor is "rgb(255, 254, 253)" PASS getComputedStyle(document.querySelectorAll(".test-case, .test-case :not(target)")[3]).backgroundColor is "rgb(255, 254, 253)" PASS getComputedStyle(document.querySelectorAll(".test-case, .test-case :not(target)")[4]).backgroundColor is "rgb(255, 254, 253)" PASS getComputedStyle(document.querySelectorAll(".test-case, .test-case :not(target)")[5]).backgroundColor is "rgb(255, 254, 253)" PASS getComputedStyle(document.querySelectorAll(".test-case, .test-case :not(target)")[6]).backgroundColor is "rgb(255, 254, 253)" PASS getComputedStyle(document.querySelectorAll(".test-case, .test-case :not(target)")[7]).backgroundColor is "rgb(255, 254, 253)" PASS getComputedStyle(document.querySelectorAll(".test-case, .test-case :not(target)")[8]).backgroundColor is "rgb(255, 254, 253)" PASS getComputedStyle(document.querySelectorAll(".test-case, .test-case :not(target)")[9]).backgroundColor is "rgb(255, 254, 253)" PASS getComputedStyle(document.querySelectorAll("target")[0]).backgroundColor is "rgb(1, 2, 3)" PASS getComputedStyle(document.querySelectorAll("target")[1]).backgroundColor is "rgb(1, 2, 3)" PASS elementsWithTagnameNeedsStyleRecalc([]) is true Let's remove the class "property". Target should require a style recalc. PASS elementsWithTagnameNeedsStyleRecalc(["TARGET"]) is true We should no longer have a match. Let's add back the class "property". Then we get the style of everything except and . Since none of the style touched above are related to the dirty elements, should still require a style recalc. PASS getComputedStyle(document.querySelectorAll(".test-case, .test-case :not(target)")[0]).backgroundColor is "rgb(255, 254, 253)" PASS getComputedStyle(document.querySelectorAll(".test-case, .test-case :not(target)")[1]).backgroundColor is "rgb(255, 254, 253)" PASS getComputedStyle(document.querySelectorAll(".test-case, .test-case :not(target)")[2]).backgroundColor is "rgb(255, 254, 253)" PASS getComputedStyle(document.querySelectorAll(".test-case, .test-case :not(target)")[3]).backgroundColor is "rgb(255, 254, 253)" PASS getComputedStyle(document.querySelectorAll(".test-case, .test-case :not(target)")[4]).backgroundColor is "rgb(255, 254, 253)" PASS getComputedStyle(document.querySelectorAll(".test-case, .test-case :not(target)")[5]).backgroundColor is "rgb(255, 254, 253)" PASS getComputedStyle(document.querySelectorAll(".test-case, .test-case :not(target)")[6]).backgroundColor is "rgb(255, 254, 253)" PASS getComputedStyle(document.querySelectorAll(".test-case, .test-case :not(target)")[7]).backgroundColor is "rgb(255, 254, 253)" PASS getComputedStyle(document.querySelectorAll(".test-case, .test-case :not(target)")[8]).backgroundColor is "rgb(255, 254, 253)" PASS getComputedStyle(document.querySelectorAll(".test-case, .test-case :not(target)")[9]).backgroundColor is "rgb(255, 254, 253)" PASS getComputedStyle(document.querySelectorAll("target")[0]).backgroundColor is "rgb(255, 254, 253)" PASS getComputedStyle(document.querySelectorAll("target")[1]).backgroundColor is "rgb(255, 254, 253)" PASS elementsWithTagnameNeedsStyleRecalc(["TARGET"]) is true We should match again now that property is back. PASS getComputedStyle(document.querySelectorAll(".test-case, .test-case :not(target)")[0]).backgroundColor is "rgb(255, 254, 253)" PASS getComputedStyle(document.querySelectorAll(".test-case, .test-case :not(target)")[1]).backgroundColor is "rgb(255, 254, 253)" PASS getComputedStyle(document.querySelectorAll(".test-case, .test-case :not(target)")[2]).backgroundColor is "rgb(255, 254, 253)" PASS getComputedStyle(document.querySelectorAll(".test-case, .test-case :not(target)")[3]).backgroundColor is "rgb(255, 254, 253)" PASS getComputedStyle(document.querySelectorAll(".test-case, .test-case :not(target)")[4]).backgroundColor is "rgb(255, 254, 253)" PASS getComputedStyle(document.querySelectorAll(".test-case, .test-case :not(target)")[5]).backgroundColor is "rgb(255, 254, 253)" PASS getComputedStyle(document.querySelectorAll(".test-case, .test-case :not(target)")[6]).backgroundColor is "rgb(255, 254, 253)" PASS getComputedStyle(document.querySelectorAll(".test-case, .test-case :not(target)")[7]).backgroundColor is "rgb(255, 254, 253)" PASS getComputedStyle(document.querySelectorAll(".test-case, .test-case :not(target)")[8]).backgroundColor is "rgb(255, 254, 253)" PASS getComputedStyle(document.querySelectorAll(".test-case, .test-case :not(target)")[9]).backgroundColor is "rgb(255, 254, 253)" PASS getComputedStyle(document.querySelectorAll("target")[0]).backgroundColor is "rgb(1, 2, 3)" PASS getComputedStyle(document.querySelectorAll("target")[1]).backgroundColor is "rgb(1, 2, 3)" Removing the should invalidate the , and nothing else. PASS elementsWithTagnameNeedsStyleRecalc(["TARGET"]) is true We should no longer match. PASS getComputedStyle(document.querySelectorAll(".test-case, .test-case :not(target)")[0]).backgroundColor is "rgb(255, 254, 253)" PASS getComputedStyle(document.querySelectorAll(".test-case, .test-case :not(target)")[1]).backgroundColor is "rgb(255, 254, 253)" PASS getComputedStyle(document.querySelectorAll(".test-case, .test-case :not(target)")[2]).backgroundColor is "rgb(255, 254, 253)" PASS getComputedStyle(document.querySelectorAll(".test-case, .test-case :not(target)")[3]).backgroundColor is "rgb(255, 254, 253)" PASS getComputedStyle(document.querySelectorAll(".test-case, .test-case :not(target)")[4]).backgroundColor is "rgb(255, 254, 253)" PASS getComputedStyle(document.querySelectorAll(".test-case, .test-case :not(target)")[5]).backgroundColor is "rgb(255, 254, 253)" PASS getComputedStyle(document.querySelectorAll(".test-case, .test-case :not(target)")[6]).backgroundColor is "rgb(255, 254, 253)" PASS getComputedStyle(document.querySelectorAll(".test-case, .test-case :not(target)")[7]).backgroundColor is "rgb(255, 254, 253)" PASS getComputedStyle(document.querySelectorAll("target")[0]).backgroundColor is "rgb(255, 254, 253)" PASS getComputedStyle(document.querySelectorAll("target")[1]).backgroundColor is "rgb(255, 254, 253)" PASS successfullyParsed is true TEST COMPLETE