LiveScript

LiveScript

LiveScript is an in-game JavaScript and Lua scripting mod for NeoForge 1.21.1.
It combines the flexibility of KubeJS with the live editing experience of ComputerCraft — but with a modern fullscreen editor directly inside Minecraft.

Security & Sandboxing

LiveScript embeds Mozilla Rhino (JavaScript) and LuaJ (Lua) as sandboxed scripting engines. Scripts cannot:

• Access the filesystem (java.io.File, java.nio.file.* blocked)
• Start subprocesses (java.lang.Runtime, java.lang.ProcessBuilder blocked)
• Use reflection (java.lang.reflect.* blocked)
• Make network requests (java.net.* blocked)

Each script has a 5-second CPU timeout. Only server operators (permission level 2, i.e. /op) can open the editor or execute scripts. The /scripteditor command uses the same permission gate as /give or /setblock.

This is the same security model as KubeJS, GroovyScript, CraftTweaker, and ComputerCraft.

Full source code: https://github.com/GrafKakashi/livescript — verify the sandbox in JsEngine.java and LuaEngine.java.

Features

• Fullscreen in-game code editor
• JavaScript (Rhino) and Lua (LuaJ) support
• Live script execution and hot-reload
• Syntax highlighting
• Autocomplete
• Undo / Redo
• Code folding
• Find & Replace
• Runtime event APIs
• Recipe manipulation APIs
• Custom item registration via items.json with runtime textures
• Tag and item utilities
• Startup scripts with priority ordering
• Built-in script console
• Sandbox and timeout protection
• CurseForge update notifications for operators

Included APIs

Events

Listen to gameplay events like:

• player.join, player.leave, player.chat, player.death, player.respawn, player.dimension_change
• block.break, block.place
• item.craft, item.smelt, item.use, item.use_block, item.pickup
• entity.spawn, entity.death, entity.damage
• mob.target
• explosion.start, explosion.detonate
• server.tick

Recipes

Add or remove recipes at runtime — all 5 cooking types (smelting, smoking, blasting, campfire, stonecutting) plus shaped/shapeless crafting:

“`javascript
recipe.shapedAdd({
id: ‘livescript:magic_diamond’,
pattern: [‘DDD’, ‘DND’, ‘DDD’],
key: { D: ‘minecraft:diamond’, N: ‘minecraft:nether_star’ },
result: {
item: ‘minecraft:diamond’,
name: ‘§bMagic Diamond’,
lore: [‘§7Pulsates with arcane energy’],
glow: true
}
});

recipe.removeByOutput(‘minecraft:torch’);
“`

Custom Items

Define custom items in config/livescript/items.json, drop PNG textures in config/livescript/textures/, restart server:

“`json
{
"items": {
"magic_dust": {
"display_name": "Magic Dust",
"max_stack_size": 64,
"rarity": "rare"
}
}
}
“`

Tags & Items

tag.itemsIn('minecraft:logs'), tag.itemHas(itemStack, 'minecraft:logs'), item.byId('minecraft:diamond'), and more.

Quick Start

1. Install the mod (NeoForge 1.21.1)
2. Start your world / server
3. As operator, run /scripteditor
4. Press the + button, create example.js, write some code, click Save & Run

Links

• Source: https://github.com/GrafKakashi/livescript
• Issues: https://github.com/GrafKakashi/livescript/issues
• License: MIT

Compatibility

• Minecraft 1.21.1 only
• NeoForge 21.1+
• Works alongside KubeJS, CC: Tweaked, and other scripting mods (no classpath conflicts thanks to shaded Rhino/LuaJ)