Note: If you are a script developer (i.e. pack dev, server admin, etc.), you likely want to visit our wiki instead.

(For a Table Of Contents, click the menu icon in the top left!)

Introduction

KubeJS is a Minecraft mod which lets you create scripts in the JavaScript programming language to manage your server using events, change recipes, add and edit (coming soon!) loot tables, customise your world generation, add new blocks and items, or use custom integration with other mods like FTB Quests for even more advanced features!

Issues and Feedback

If you think you've found a bug with the mod or want to ask for a new feature, feel free to open an issue here on GitHub, we'll try to get on it as soon as we can! Alternatively, you can also discuss your feature requests and suggestions with others using the Discussions tab.

And if you're just looking for help with KubeJS overall and the wiki didn't have the answer for what you were looking for, you can join our Discord server and ask for help in the support channels, as well!

License

KubeJS is distributed under the GNU Lesser General Public License v3.0, or LGPLv3. See our LICENSE file for more information.

Creating addons

Creating addon mods for KubeJS is easy! Just follow the following steps to your own liking, depending on how deep you want your integration to go!

Those are lies and deceit.

To add a Gradle dependency on KubeJS, you will need to add the following repositories to your build.gradle's repositories:

repositories {
    maven {
        url "https://maven.latvian.dev/releases"
        content {
            includeGroup "dev.latvian.mods"
            includeGroup "dev.latvian.apps"
        }
    }

    maven {
        url 'https://jitpack.io'
        content {
            includeGroup "com.github.rtyley"
        }
    }
}

You can then declare KubeJS as a regular compile-time dependency in your dependencies block:

api("dev.latvian.mods:kubejs-neoforge:${kubejs_version}")

Just set the versions with most up-to-date version of the required mod(s), which you also find using these badges:

(Note: The above badges may not represent the true latest version of these mods. As a basic rule of thumb, for KubeJS and Rhino, you should always be using the latest version compiled against your version of Minecraft, for example 1802.+ for Minecraft 1.18.2, while for Architectury, the corresponding major version will be provided. You can also click on the badge to see all versions of each mod)

Creating a plugin

KubeJS plugins are the main way to add KubeJS integration to your mods through code. They contain various convenient hooks for addon developers, to allow things such as:

• performing certain actions during or after plugin or KubeJS initialisation (init, afterInit, etc.)
• adding classes to the class filter (registerClasses) as well as custom bindings (registerBindings) and type wrappers (registerWrappers) for easier interaction with native code in user scripts (See below for an explanation and example use cases)
• registering custom recipe handlers for modded recipe types (registerRecipeTypes - See below for an example)
• registering custom event handler groups for the KubeJS event system (registerEvents, this is necessary in order to have the event group be accessible from scripts)
• attaching extra data to players, worlds or the server, such that it can be accessed by script developers later (attach(Player|World|Server)Data - Example)

You must add your plugin class in a src/main/resources/kubejs.plugins.txt file, optionally with mod id at end, e.g.:

dev.latvian.mods.kubejs.mekanism.MekanismKubeJSPlugin mekanism

Adding bindings

Similarly to adding custom recipe types, you may also add custom bindings to KubeJS (see AntimatterAPI for a simple example). Bindings can be anything from single value constants (like the global HOUR = 3600000 (ms)) to Java class and method wrappers (such as the builtin Item binding, which is wrapping the ItemWrapper class), and can be constrained to individual scopes, contexts and script types, as well!

Setting class filters

KubeJS offers native Java type access in script files, meaning that basic Java types can be referenced directly by using for example Java.loadClass("package.class"). While builtin filters exist to prevent users from accessing any internal or potentially harmful packages added by Minecraft or its libraries directly, you may still want to explicitly deny access to certain classes or packages in your mod (or explicitly allow certain classes within a generally blacklisted package). To do this, you may either provide a class filter using a KubeJS plugin or you can avoid adding KubeJS as a dependency entirely by providing a simple kubejs.classfilter.txt file in your mod's resources with the following format (Note that comments aren't allowed in the actual file):

+mymod.api // This will *explicitly allow* anything from the mymod.api package to be used in KubeJS
-mymod.api.MyModAPIImpl // This will deny access to the MyModAPIImpl class, while keeping the rest of the package accessible
-mymod.internal.HttpUtil // This will *explicitly deny* your class from being used in KubeJS

Contributing to KubeJS

Getting Started

If you want to contribute to KubeJS, you will first need to set up a development environment, which should be fairly simple. Just clone the repository using Git:

git clone https://github.com/KubeJS-Mods/KubeJS.git

and import the gradle project using an IDE of your choice!

Building

Building KubeJS from source should be rather straightforward, as well, just run gradlew build in the root project, and the jar files should be in build/libs directory (kubejs-<loader>-<version>.jar).

Creating Pull Requests

When creating a pull request to KubeJS, please make sure you acknowledge the following:

• We will usually not accept pull requests that add mod-specific support; those things are better suited as KubeJS plugins (optimally within the target mods themselves) or integration mods.
• Please be sure to test your feature before creating a pull request. We are a rather small team and as such, can't spend all too much time on reviewing pull requests.
• While not strictly required, please try to adhere by the repository's code style and conventions. A sample .editorconfig file exists to make this even easier for you to achieve (see the relevant EditorConfig plugin for your IDE)
• If you are unsure whether your feature fits into KubeJS and would like to hear additional opinions on the matter, feel free to open an issue or a discussion to discuss it further with us first!