This test checks whether various forms of preincrement expression are allowed. On success, you will see a series of "PASS" messages, followed by "TEST COMPLETE". PASS ++x is 1 PASS ++window.x is 2 PASS ++window["x"] is 3 PASS ++(x) is 4 PASS ++(window.x) is 5 PASS ++(window["x"]) is 6 PASS (y, ++x) is 7 PASS ++((x)) is 8 PASS ++((window.x)) is 9 PASS ++((window["x"])) is 10 PASS ++(y, x) threw exception ReferenceError: Prefix ++ operator applied to value that is not a reference.. PASS ++(true ? x : y) threw exception ReferenceError: Prefix ++ operator applied to value that is not a reference.. PASS ++++x threw exception ReferenceError: Prefix ++ operator applied to value that is not a reference.. PASS successfullyParsed is true TEST COMPLETE