I’ve only written a small amount of JavaScript that runs embedded in a Java application, but it was tested using QUnit, has been mixed, and I’ve not noticed any problems yet.
Is there some conventional wisdom whether to use semicolons or not in JavaScript?
Use them. Use them constantly.
It’s far too easy to have something break later on because you neglected a semi-colon and it lost the whitespace which saved it before in a compression/generation/eval parse.