EventJS for Minecraft: Reloadable Forge Native Events in KubeJS
If you script Minecraft with KubeJS and Forge, you have probably bumped into a frustrating limit: native event hooks often feel “baked in” until you restart the whole game. EventJS is a KubeJS addon that changes that story. It layers reloadable native events on top of KubeJS so you can iterate on listeners, recover from mistakes more safely, and keep your modpack workflow moving without constant relaunches.
Why EventJS Exists
KubeJS is excellent for recipes, tags, and rapid scripting, but historically it did not make Forge’s native event bus easy to refresh on older game lines. For versions between 1.16 and 1.20, reloading native listeners was essentially off the table, which meant every tweak to a handler could cost you a full client or server restart. EventJS was built to fill that gap: it brings a practical, performant pattern for native events where KubeJS itself was slow to ship parity. If you maintain a curated mod list and want smoother pack development, tooling that trims restart cycles matters a lot.
What EventJS Actually Does
At a high level, EventJS adds reloadable native events for KubeJS. That means you can refresh native event listeners without restarting Minecraft, attach and detach handlers more freely, and avoid the old “everything is global state and hope for the best” workflow. You can also store handlers in something like global['someId'] for a simpler mental model and better performance characteristics than repeatedly fighting the lifecycle of one-off scripts.
Quality-of-life wins stack up quickly:
- Add and remove listeners on demand without a full relaunch, which used to be impractical on KubeJS for 1.16 through 1.20.
- Reduce crash risk when a native listener misbehaves, so a scripting mistake is less likely to take the session down hard.
- Side-aware listening so you can register client-only logic in client scripts and keep server scripts clean, matching how Minecraft itself splits concerns.
Default Behavior vs. Explicit APIs
By default, EventJS replaces the original native event listening path with a reload-friendly version. In practice, you do not need a new mental model just to benefit: install the addon, keep writing KubeJS, and Forge event listening becomes reloadable. If you want more control, EventJS exposes NativeEvents helpers for clearer, dynamic registration.
Across client, server, and startup script types, NativeEvents is available so you can express sided listening explicitly. For example, a listener defined under client scripts will not run on the dedicated server, which keeps tick-sensitive UI or rendering hooks from polluting server logic.
Pack authors who juggle dozens of mods often route installs through dedicated launch profiles; if you prefer a launcher that stays out of your way while you test scripting changes, this mod can be easily installed via the foxygame.net launcher, a convenient, flexible, and modern Minecraft launcher where you can download mods right from the menu, which pairs nicely with rapid KubeJS iteration.
Syntax Overview (v1.0.0 through 1.3.0)
For detailed handler wiring, EventJS follows familiar Forge-shaped patterns expressed in JavaScript. The handler is a callback receiving the event object, such as (event) => { ... }. Event types can be represented as strings with the class name or as classes loaded through java(...) or Java.loadClass(...), depending on your environment.
NativeEvents.onEvent(eventType, handler)NativeEvents.onEvent(priority, receiveCancelled, eventType, handler)NativeEvents.onGenericEvent(genericClassFilter, eventType, handler)NativeEvents.onGenericEvent(genericClassFilter, priority, receiveCancelled, eventType, handler)
Parameters map to Forge expectations: priority can be an $EventPriority value or one of highest, high, normal, low, lowest, while receiveCancelled is a boolean gate for cancelled events.
What Changed in 1.4.0
Starting with EventJS 1.4.0, compatibility with ProbeJS Legacy is prioritized out of the box. As a result, eventType and genericClassFilter are expected to be Class references loaded via java(...) on 1.16.5 or Java.loadClass(...) on 1.20.1, rather than loose string forms. Treat that shift as part of your update checklist when you bumpaddon versions alongside KubeJS, Forge, and your other mods.
Supported Versions and Forks in Naming
Coverage evolves by release line: early builds targeted 1.16.5, wider support stretched across majors between 1.16 and 1.20, and multi-version packs should confirm the exact EventJS build against their KubeJS and Forge stack. Also note that KubeJS 1.21+ ships a feature also called NativeEvents, but it is not the same implementation as EventJS. Avoid mixing assumptions about internals when bridging Java-side hooks or debugging classloader edge cases.
Practical Takeaways for Modded Servers and Packs
EventJS is not about replacing KubeJS; it is about making native Forge mechanics feel as nimble as the rest of your scripting layer. Use it when you need responsive event iteration, safer failure modes, and explicit sided registration. Pair it with disciplined script organization, version-locked dependencies, and clear separation between client and server listeners, and your biomes, blocks, and custom mechanics will be easier to tune under real server load.
In short, EventJS turns a long-standing KubeJS limitation into a workflow feature: reloadable native events, cleaner handler storage, and Forge-aware listening that respects Minecraft’s sides. That is the kind of quality-of-life upgrade modders notice immediately once they stop relaunching for every small bus tweak.