User blog comment:Rappy 4187/Technical Update: August 31, 2015/@comment-25648422-20150902145646/@comment-24473195-20150902151158

All Wiki's javascript will not likely ever be fully editable again. At least not in the previous manner. I'm guessing that admins will be able to create scripts and debug them in some sort of sandbox, and once they are confident that it works  then submit it for review and it may become "live" if there aren't serious security problems.