This test should trigger exceptions on HTMLTableElement, and verify that the messages are reasonably helpful. On success, you will see a series of "PASS" messages, followed by "TEST COMPLETE". PASS t.insertRow(-2) threw exception IndexSizeError: Failed to execute 'insertRow' on 'HTMLTableElement': The index provided (-2) is less than -1.. PASS t.insertRow(1) threw exception IndexSizeError: Failed to execute 'insertRow' on 'HTMLTableElement': The index provided (1) is greater than the number of rows in the table (0).. PASS t.deleteRow(-2) threw exception IndexSizeError: Failed to execute 'deleteRow' on 'HTMLTableElement': The index provided (-2) is less than -1.. PASS t.deleteRow(2) threw exception IndexSizeError: Failed to execute 'deleteRow' on 'HTMLTableElement': The index provided (2) is greater than the number of rows in the table (1).. PASS successfullyParsed is true TEST COMPLETE