Overview of KubeJS
KubeJS is a Minecraft mod created by Lat that enables game customization through scripts written in the JavaScript programming language. Distributed under the GNU Lesser General Public License v3.0, the mod falls into the Libraries & APIs and Utility & Quality of Life categories. Installation is optional on both the client side and the server side. It supports the Neoforge mod loader on Minecraft versions 26.1.2, 1.21.1, and 1.21.
The mod allows creators to manage servers, modify recipes, customize world generation, and add new blocks and items. Scripts can also manage tags, handle world events, and provide custom handlers or integrations with other mods such as FTB Quests.
Script Types and Reloading
Running the game once with the mod installed generates a kubejs folder containing example scripts in the Minecraft directory. The mod uses distinct script types for different tasks:
- Startup scripts: These run once when the game loads and are used for registering items and setting up configs.
- Server and data scripts: These load when joining a world and handle player or world tasks, such as displaying custom login messages or running clearlag.
Users can reload scripts with the /reload command. While some modifications work on the fly, certain changes require restarting the world or restarting the game.
Plugin Architecture and Java Integration
For addon developers, KubeJS features a plugin architecture configured through a kubejs.plugins.txt file. Plugins can execute actions during or after initialization, register custom recipe types, register custom event handler groups for scripts, and attach extra data to players, worlds, or the server. Addons can also add custom bindings ranging from constant values to Java class and method wrappers.
Scripts can access native Java types directly using Java.loadClass. Real talk, built-in filters prevent access to internal or dangerous packages, and developers can further customize allowed or denied classes through plugins or by providing a kubejs.classfilter.txt file.
Community and Support
Example scripts, pre-made scripts, and documentation can be found on the KubeJS Wiki. For additional assistance, bug reports, questions, and feature suggestions, users can participate in GitHub issues, GitHub discussions, and Discord support channels.
