If you wanted a user scripting feature and not Javascript in particular, then couldn't you embed the Scala REPL with appropriate resource usage limits? You can

If you wanted a user scripting feature and not Javascript in particular, then couldn't you embed the Scala REPL with appropriate resource usage limits? You can using Apache Groovy which is used by Gradle and Jenkins Pipelines. Of course Scala and Javascript are both rising in adoption, whereas Groovy is fast sinking so you probably wouldn't want to go that way.