In tests/auto/qscriptjstestsuite/tst_qscriptjstestsuite.cpp, a lot of the JS tests are flagged as expected failures, typically with the generic failure message "Will fix in next release".
This is rather meaningless.
Since QtScript no longer uses an in-house-developed JavaScript engine, the failure messages should contain links to corresponding upstream bugs (at http://bugs.webkit.org), so that somebody might perhaps fix these issues.