Scripting

NOTICE

This page refers to the legacy Javascript scripting which is no longer fully supported. The main scripting support available in modern Citizens is through Denizen.

Scripting Support in Citizens2

Citizens2 includes support for various scripting languages including Lua, Javascript and Python.

Javascript support is built into Java; additional languages can be added in through installing things such as JRuby (http://jruby.org/), Jython (http://www.jython.org/), Kahlua (https://github.com/krka/kahlua2) and more.

The scripting API contains a few built in objects in the global namespace which aid in some tasks. Currently, the 'events' object allows registering event listeners for Bukkit events and a reference to the Citizens plugin object is available under 'plugin'.

Behaviours

Let's see an example of how to use scripts. Scripts can be added to an NPC via the /npc script --add [scripts] command, where scripts is a list of files inside the plugins/Citizens/scripts folder to use. Scripts are differentiated by their extension -- make sure it is correct!

When the script file is loaded by Citizens, it will call the method 'onLoad(NPC)' - anything can be performed at this time, although the NPC will not necessarily be spawned. If the method 'run(NPC)' exists it will also be called every tick by Citizens.

   function leftClick(event) {
       event.getClicker().sendMessage("hello from Javascript scripting!");
   }

   function onLoad(npc) {
       events.on(Java.type('net.citizensnpcs.api.event.NPCLeftClickEvent').class, leftClick);
   }

Scripting Gotchas and Tips

Javascript (Nashorn)

• Nashorn is a much faster Javascript engine only included in Java 7 and above. It is recommended to run this over the older Rhino engine.
• Read https://docs.oracle.com/javase/8/docs/technotes/guides/scripting/nashorn/api.html for more information on Java-Javascript connection.

Javascript (Rhino)

• Some code will expect the methods equals and hashcode to be implemented - a simple equals function should be used often.
• for.. in loops do not work with Java collections.
• Rhino cannot use abstract classes.
• You can implement Java interfaces by using new [interfacename](object), where object contains the methods implementing the interface.
• Use importPackage(Packages.name.space) or importClass(Packages.name.space.YourClass) to import other classes/packages. The Packages. prefix is not required if the class is in the java.util package.