GitHub does provide an option to search issues by language.
Sergey "Shnatsel" Davidoff
51

You are right, this query gets all open Javascript issues (basically what you did without the ‘unsound’ option: https://github.com/issues?utf8=%E2%9C%93&q=is%3Aopen+is%3Aissue+archived%3Afalse+language%3Ajavascript+.

So I should edit my post a little, thanks for the catch!