Events

Events that get fired during game to control recipes, world, etc.

List of all events

This is a list of all events. It's possible that not all events are listed here, but this list will be updated regularly.

Click on event ID to open it's class and see information, fields and methods.

Type descriptions:

ID Cancellable Type Note
init No Startup
postinit No Startup
loaded No Startup
command.registry No Server
command.run Yes Server
client.init No Client
client.debug_info.left No Client
client.debug_info.right No Client
client.generate_assets No Client
client.logged_in No Client
client.logged_out No Client
client.tick No Client
server.load No Server
server.unload No Server
server.tick No Server
server.datapack.first No Server
server.datapack.last No Server
recipes No Server
recipes.after_load No Server Does not work 1.18+
level.load No Server Replace level with world in 1.16
level.unload No Server Replace level with world in 1.16
level.tick No Server Replace level with world in 1.16
level.explosion.pre Yes Server Replace level with world in 1.16
level.explosion.post No Server Replace level with world in 1.16
player.logged_in No Server
player.logged_out No Server
player.tick No Server
player.data_from_server. Yes Client
player.data_from_client. Yes Server
player.chat Yes Server
player.advancement No Server
player.inventory.opened No Server
player.inventory.closed No Server
player.inventory.changed No Server
player.chest.opened No Server
player.chest.closed No Server
entity.death Yes Server
entity.attack Yes Server
entity.drops Yes Server
entity.check_spawn Yes Server
entity.spawned Yes Server
block.registry No Startup
block.missing_mappings No Server
block.tags No Server
block.right_click Yes Server
block.left_click Yes Server
block.place Yes Server
block.break Yes Server
block.drops No Server
item.registry No Startup
item.missing_mappings No Server
item.tags No Server
item.right_click Yes Server
item.right_click_empty No Server
item.left_click No Server
item.entity_interact Yes Server
item.modification No Startup
item.pickup Yes Server
item.tooltip No Client
item.toss Yes Server
item.crafted No Server
item.smelted No Server
fluid.registry No Startup
fluid.tags No Server
entity_type.tags No Server
worldgen.add No Startup
worldgen.remove No Startup


Custom Items

This is a startup_scripts/ event

// Listen to item registry event
onEvent('item.registry', event => {
  
  // The texture for this item has to be placed in kubejs/assets/kubejs/textures/item/test_item.png
  // If you want a custom item model, you can create one in Blockbench and put it in kubejs/assets/kubejs/models/item/test_item.json
  event.create('test_item')
  
  // You can chain builder methods as much as you like
  event.create('test_item_2').maxStackSize(16).glow(true)
  
  // You can specify item type as 2nd argument in create(), some types have different available methods
  event.create('custom_sword', 'sword').tier('diamond').attackDamageBaseline(10.0)
})
Valid item types:

Other methods item builder supports:

You can chain these methods after create()

Anything with a ??? may not be completely accurate

Physical Properties
Non-Model Visual Stuff
Model Editing

There is an example below

Bar

There an example farther below

Custom Uses

The is a section below for an example

Miscellaneous
Tool

Methods available if you use 'sword', 'pickaxe', 'axe', 'shovel' or 'hoe' type:

Armor

Methods available if you use 'helmet', 'chestplate', 'leggings' or 'boots' type:

Creating custom tool and armor tiers

All values are optional and by default are based on iron tier

onEvent('item.registry.tool_tiers', event => {
  event.add('tier_id', tier => {
    tier.uses = 250
    tier.speed = 6.0
    tier.attackDamageBonus = 2.0
    tier.level = 2
    tier.enchantmentValue = 14
    tier.repairIngredient = '#forge:ingots/iron'
  })
})
onEvent('item.registry.armor_tiers', event => {
  // Slot indicies are [FEET, LEGS, BODY, HEAD]
  event.add('tier_id', tier => {
    tier.durabilityMultiplier = 15 // Each slot will be multiplied with [13, 15, 16, 11]
    tier.slotProtections = [2, 5, 6, 2]
    tier.enchantmentValue = 9
    tier.equipSound = 'minecraft:item.armor.equip_iron'
    tier.repairIngredient = '#forge:ingots/iron'
    tier.toughness = 0.0 // diamond has 2.0, netherite 3.0
    tier.knockbackResistance = 0.0
  })
})

Examples:

Custom Foods

These methods are each optional, and you may include as many or as few as you like.

onEvent('item.registry', event => {
	event.create('magic_steak').food(food => {
		food
    		.hunger(6)
    		.saturation(6)//This value does not directly translate to saturation points gained
      		//The real value can be assumed to be:
      		//min(hunger * saturation * 2 + saturation, foodAmountAfterEating)
      		.effect('speed', 600, 0, 1)
      		.removeEffect('poison')
      		.alwaysEdible()//Like golden apples
      		.fastToEat()//Like dried kelp
      		.meat()//Dogs are willing to eat it
      		.eaten(ctx => {//runs code upon consumption
        		ctx.player.tell('Yummy Yummy!')
          		//If you want to modify this code then you need to restart the game.
          		//However, if you make this code call a global startup function
          		//and place the function *outside* of an 'onEvent'
          		//then you may use the command:
          		//  /kubejs reload startup_scripts
          		//to reload the function instantly.
        	})
	})
})
Custom Uses
onEvent("item.registry", event => {
event.create("nuke_soda", "basic")
        .tooltip("§5Taste of Explosion!")
        .tooltip("§c...Inappropriate intake may cause disastrous result.")
        /**
         * The use animation of the item, can be  "spear" (trident),
         * "crossbow", "eat" (food), "spyglass", "block", "none", "bow", "drink"
         * When using certain animations, corresponding sound will be played.
         */
        .useAnimation("drink")
        /**
         * The duration before the item finishs its using,
         * if you need something like hold-and-charge time (like bow),
         * consider set this to 72000 (1h) or more.
         * A returned value of 0 or lower will render the item not usable.
         */
        .useDuration((itemstack) => 64)
        /**
         * When item is about to be used.
         * If true, item will starts it use animation if duration > 0.
         */
        .use((level, player, hand) => true)
        /**
         * When the item use duration expires.
         */
        .finishUsing((itemstack, level, entity) => {
            let effects = entity.potionEffects;
            effects.add("haste", 120 * 20)
            itemstack.itemStack.shrink(1)
            if (entity.player) {
                entity.minecraftPlayer.addItem(Item.of("minecraft:glass_bottle").itemStack)
            }
            return itemstack;
        })
        /**
         * When the duration is not expired yet, but
         * players release their right button.
         * Tick is how many ticks remained for player to finish using the item.
         */
        .releaseUsing((itemstack, level, entity, tick) => {
            itemstack.itemStack.shrink(1)
            level.createExplosion(entity.x, entity.y, entity.z).explode()
        })
})
Bar
event.create("hammer")
        //Determine how long the bar is, should be an integer between 0 (empty) and 13 (full)
        //If the value is below 0, it will be treated as 0.
        //The value is capped at 13, any value over 13 will be considered "full", thus making it not shown
        .barWidth(i => i.nbt.contains("hit_count") ? i.nbt.getInt("hit_count") / 13.0 : 0)
        //Determine what color should the bar be.
        .barColor(i => Color.AQUA)
Dynamic Tinting and Model Stuff
onEvent("item.registry", (event) => {
	/**
	 * Old style with just setting color by index still works!
	 */
	event
		.create("old_color_by_index")
		.textureJson({
			layer0: "minecraft:item/paper",
			layer1: "minecraft:item/ghast_tear",
		})
		.color(0, "#70F00F")
		.color(1, "#00FFF0");

	event
		.create("cooler_sword", "sword")
		.displayName("Test Cooler Sword")
		.texture("minecraft:item/iron_sword")
		.color((itemstack) => {
			/**
			 * Example by storing the color in the nbt of the itemstack
			 * You have to return -1 to apply no tint.
			 *
			 * U can test this through: /give @p kubejs:cooler_sword{color:"#ff0000"}
			 */
			if (itemstack.nbt && itemstack.nbt.color) {
				return itemstack.nbt.color;
			}

			return -1;
		});

	event
		.create("test_item")
		.displayName("Test Item")
		.textureJson({
			layer0: "minecraft:item/beef",
			layer1: "minecraft:item/ghast_tear",
		})
		.color((itemstack, tintIndex) => {
			/**
			 * If you want to apply the color to a specific layer, you can use the tintIndex
			 * tintIndex is the texture layer index from the model: layer0 -> 0, layer1 -> 1, etc.
			 * U can use the `Color` wrapper for some default colors
			 *
			 * This example will apply the color to the ghast_tear texture.
			 */
			if (tintIndex == 1) {
				return Color.BLUE;
			}
			return -1;
		});

	/**
	 * Set a texture for a specific layer
	 */
	event.create("test_sword", "sword").displayName("Test Sword").texture("layer0", "minecraft:item/bell");

	/**
	 * Directly set your custom model json
	 */
	event.create("test_something").displayName("Test something").modelJson({
		parent: "minecraft:block/anvil",
	});
});

EventJS

This event is the most basic event class, parent of all other events.

Parent class

Object

Can be cancelled

No

Variables and Functions

Name Return Type Info
cancel() void Cancels event. If the event can't be cancelled, it won't do anything.

Custom Blocks


This is a startup script.

onEvent('block.registry', event => {
  event.create('test_block')
  	   .material('glass')
       .hardness(0.5)
       .displayName('Test Block') // No longer required in 1.18.2+
       .tagBlock('minecraft:mineable/shovel') // Make it mine faster using a shovel in 1.18.2+
  	   .tagBlock('minecraft:needs_iron_tool') // Make it require an iron or higher level tool on 1.18.2+
  	   .requiresTool(true) // Make it require a tool to drop ay loot
  
  // Block with custom type (see below for list of types for 1.18 (use .type for 1.16))
  event.create('test_block_slab', 'slab').material('glass').hardness(0.5)
  
  
  //uses a combo of properties (things you might consider blockstate) and random tick to make the block eventually change to test_block, but only progresses if waterlogged
  event.create('test_block_2').material('glass').hardness(0.2).property(BlockProperties.WATERLOGGED).property(BlockProperties.AGE_7).randomTick(tick => {
    const block = tick.block
    const properties = block.properties
    const age = Number(properties.age)
    if (properties.waterlogged == 'false') return
    if (age == 7) {
      block.set('kubejs:test_block')
    } else {
      block.set('kubejs:test_block_2',{waterlogged:'true',age:`${age+1}`})
  })
})


The texture for this block has to be placed in kubejs/assets/kubejs/textures/block/test_block.png.
If you want a custom block model, you can create one in Blockbench and put it in kubejs/assets/kubejs/models/block/test_block.json.


List of available materials - to change break/walk sounds and to change some properties.

Materials (1.18.2)
air
wood
stone
metal
grass

dirt
water
lava
leaves
plant
sponge
wool
sand
glass
explosive
ice
snow
clay
vegetable
dragon_egg
portal
cake
web
slime
honey
berry_bush
lantern


Other methods block builder supports: 

RandomTickEvent callback properties

Block Properties

The default 1.18 properties are:

You can make your own also using the following example:

const $BooleanProperty = Java.loadClass('net.minecraft.world.level.block.state.properties.BooleanProperty')
const $IntegerProperty = Java.loadClass('net.minecraft.world.level.block.state.properties.IntegerProperty')

onEvent('block.registry', event => {
   event.create('my_block').property($IntegerProperty.create("uses", 0, 2)).property($BooleanProperty.create("empty"))
})

Types

Detector Block Types

The detector block type can be used to run code when the block is powered with redstone signal.

Startup script code:

onEvent('block.registry', event => {
  event.create('test_block','detector').detectorId('myDetector')
}

Server script code:

onEvent('block.detector.myDetector.unpowered', event => { // you can also use powered and changed instead of upowered
        event.block.set('tnt')
}

CommandEventJS

This event needs cleanup! Using it is not recommended.

Information

This event is fired when a command is executed on server side.

Parent class

EventJS

Can be cancelled

Yes

Variables and Functions

Name Type Info
parseResults ParseResults<CommandSource> Command params 
exception Exception Error, set if something went wrong



TagEventJS

This event is fired when a tag collection is loaded, to modify it with script. You can add and remove tags for items, blocks, fluids and entity types.

This goes into server scripts.

Tags are per item/block/fluid/entity type and as such cannot be added based on things like NBT data!

Parent class

EventJS

Can be cancelled

No

Variables and Functions

Name Type Info
type String Tag collection type.
get(String tag) TagWrapper Returns specific tag container which you can use to add or remove objects to. tag parameter can be something like 'forge:ingots/copper'. If tag doesn't exist, it will create a new one.
add(String tag, String[]/Regex ids) TagWrapper Shortcut method for event.get(tag).add(ids).
remove(String tag, String[]/Regex ids) TagWrapper Shortcut method for event.get(tag).remove(ids).
removeAll(String tag) TagWrapper Shortcut method for event.get(tag).removeAll().
removeAllTagsFrom(String[] ids) void Removes all tags from object

TagWrapper class

Variables and Functions

Name Type Info
add(String[]/Regex ids) TagWrapper (itself) Adds an object to this tag. If string starts with # then it will add all objects from the second tag. It can be either single string, regex (/regex/flags) or array of either.
remove(String[]/Regex ids) TagWrapper (itself) Removes an object from tag, works the same as add().
removeAll() TagWrapper (itself) Removes all entries from tag.
getObjectIds() Collection<ResourceLocation> Returns a list of all entries in a tag. Will resolve any sub-tags.

Examples

// Listen to item tag event
onEvent('item.tags', event => {
  // Get the #forge:cobblestone tag collection and add Diamond Ore to it
  event.add('forge:cobblestone', 'minecraft:diamond_ore')
  
  // Get the #forge:cobblestone tag collection and remove Mossy Cobblestone from it
  event.remove('forge:cobblestone', 'minecraft:mossy_cobblestone')
  
  // Get #forge:ingots/copper tag and remove all entries from it
  event.removeAll('forge:ingots/copper')
  
  // Required for FTB Quests to check item NBT
  event.add('itemfilters:check_nbt', 'some_item:that_has_nbt_types')
  
  // You can create new tags the same way you add to existing, just give it a name
  event.add('forge:completely_new_tag', 'minecraft:clay_ball')
  
  // Removes all tags from this entry
  event.removeAllTagsFrom('minecraft:stick')
  
  // Add all items from the forge:stone tag to the c:stone tag, unless the id contains diorite
  const stones = event.get('forge:stone').getObjectIds()
  const blacklist = Ingredient.of(/.*diorite.*/)
  stones.forEach(stone => {
    if (!blacklist.test(stone)) {
      event.add('c:stone', stone)
    }
  })
})

Recipes use item tags, not block or fluid tags, even if items representing those are blocks. Like minecraft:cobblestone even if it's a block, it will still be an item tag for recipes.

tags.blocks and tags.fluids are for adding tags to block and fluid types, they work the same way. You can find existing block and fluid tags if you look at a block with F3 mode enabled, on side. These are mostly only used for technical reasons, and like mentioned above, if its for recipes/inventory, you will want to use tags.items even for blocks.

Loot Table Modification

onEvent('block.loot_tables', event => {
  event.addSimpleBlock('minecraft:dirt', 'minecraft:red_sand')
})
onEvent('block.loot_tables', event => {
  event.addSimpleBlock('minecraft:dirt') // To drop itself (fix broken blocks)
  event.addSimpleBlock(/minecraft:.*_ore/, 'minecraft:red_sand') // To drop a different item
})
onEvent('block.loot_tables', event => {
  event.addBlock('minecraft:dirt', table => { // Build loot table manually
    table.addPool(pool => {
      pool.rolls = 1 // fixed
      // pool.rolls = [4, 6] // or {min: 4, max: 6} // uniform
      // pool.rolls = {n: 4, p: 0.3} // binominal
      pool.survivesExplosion()
      pool.addItem('minecraft:dirt')
      pool.addItem('minecraft:dirt', 40) // 40 = weight
      pool.addItem('minecraft:dirt', 40, [4, 8]) // [4-8] = count modifier, uses same syntax as rolls
      // pool.addCondition({json condition, see vanilla wiki})
      // pool.addEntry({json entry, see vanilla wiki for non-items})
    })
  })
})

Example from Factorial: (adds 1-3 leaves dropped from all Leaves blocks, 4-8 logs from all log and wood blocks and 4-8 stone from Stone, Cobblestone, Andesite, Diorite and Granite)

onEvent('block.loot_tables', event => {
	event.addBlock(/minecraft:.*_leaves/, table => {
		table.addPool(pool => {
			pool.survivesExplosion()
			pool.addItem('factorial:leaf', 1, [1, 3])
		})
	})

	event.addBlock(/minecraft:.*_(log|wood)/, table => {
		table.addPool(pool => {
			pool.survivesExplosion()
			pool.addItem('factorial:wood', 1, [4, 8])
		})
	})

	event.addBlock([
		'minecraft:stone',
		'minecraft:cobblestone',
		'minecraft:andesite',
		'minecraft:diorite',
		'minecraft:granite'
	], table => {
		table.addPool(pool => {
			pool.rolls = [4, 8] // Roll the pool instead of individual items
			pool.survivesExplosion()
			pool.addItem('factorial:stone', 1)
		})
	})
})

You can also modify existing loot tables to add items to them:

onEvent('block.loot_tables', event => {
  // all dirt blocks have a 50% chance to drop an enchanted diamond sword named "test"
  event.modifyBlock(/^minecraft:.*dirt/, table => {
    table.addPool(pool => {
      pool.addItem('minecraft:diamond_sword').randomChance(0.5).enchantWithLevels(1, true).name(Text.of('Test').blue())
    })
  })
})

Other loot table types work too:

onEvent('entity.loot_tables', event => {
  // Add a loot table for the zombie that will drop 5 of either carrot (25% chance) or apple (75% chance)
  // Because the zombie already has a loot table, this will override the current one
  event.addEntity('minecraft:zombie', table => {
    table.addPool(pool => {
      pool.rolls = 5
      pool.addItem('minecraft:carrot', 1)
      pool.addItem('minecraft:apple', 3)
    })
  })
  
  event.modifyEntity('minecraft:pig', table => {
    table.addPool(pool => {
      // Modify pig loot table to *also* drop dirt on top of its regular drops
      pool.addItem('minecraft:dirt')
    })
  })
})

Supported table types:

Event ID Override method name Modify method name
generic.loot_tables addGeneric modify
block.loot_tables addBlock modifyBlock
entity.loot_tables addEntity modifyEntity
gift.loot_tables addGift modify
fishing.loot_tables addFishing modify
chest.loot_tables addChest modify

RecipeEventJS

Examples

The most basic script to add a single recipe:

onEvent('recipes', event => {
  event.shaped('3x minecraft:stone', [
    'SAS',
    'S S',
    'SAS'
  ], {
    S: 'minecraft:sponge',
    A: 'minecraft:apple'
  })
})

The most basic script to remove a recipe:

onEvent('recipes', event => {
  event.remove({output: 'minecraft:stick'})
})

Example recipe script:

// kubejs/server_scripts/example.js
// This is just an example script to show off multiple types of recipes and removal methods
// Supports /reload

// Listen to server recipe event
onEvent('recipes', event => {
  // Remove broken recipes from vanilla and other mods
  // This is on by default, so you don't need this line
  //event.removeBrokenRecipes = true

  event.remove({}) // Removes all recipes (nuke option, usually not recommended)
  event.remove({output: 'minecraft:stone_pickaxe'}) // Removes all recipes where output is stone pickaxe
  event.remove({output: '#minecraft:wool'}) // Removes all recipes where output is Wool tag
  event.remove({input: '#forge:dusts/redstone'}) // Removes all recipes where input is Redstone Dust tag
  event.remove({mod: 'quartzchests'}) // Remove all recipes from Quartz Chests mod
  event.remove({type: 'minecraft:campfire_cooking'}) // Remove all campfire cooking recipes
  event.remove({id: 'minecraft:glowstone'}) // Removes recipe by ID. in this case, data/minecraft/recipes/glowstone.json
  event.remove({output: 'minecraft:cooked_chicken', type: 'minecraft:campfire_cooking'}) // You can combine filters, to create ANDk logic
  
  // You can use 'mod:id' syntax for 1 sized items. For 2+ you need to use '2x mod:id' or Item.of('mod:id', count) syntax. If you want NBT or chance, 2nd is required

  // Add shaped recipe for 3 Stone from 8 Sponge in chest shape
  // (Shortcut for event.recipes.minecraft.crafting_shaped)
  // If you want to use Extended Crafting, replace event.shapeless with event.recipes.extendedcrafting.shapeless_table
  event.shaped('3x minecraft:stone', [
    'SAS',
    'S S',
    'SAS'
  ], {
    S: 'minecraft:sponge',
    A: 'minecraft:apple'
  })

  // Add shapeless recipe for 4 Cobblestone from 1 Stone and 1 Glowstone
  // (Shortcut for event.recipes.minecraft.crafting_shapeless)
  // If you want to use Extended Crafting, replace event.shapeless with event.recipes.extendedcrafting.shaped_table
  event.shapeless('4x minecraft:cobblestone', ['minecraft:stone', '#forge:dusts/glowstone'])

  // Add Stonecutter recipe for Golden Apple to 4 Apples
  event.stonecutting('4x minecraft:apple', 'minecraft:golden_apple')
  // Add Stonecutter recipe for Golden Apple to 2 Carrots
  event.stonecutting('2x minecraft:carrot', 'minecraft:golden_apple')

  // Add Furnace recipe for Golden Apple to 3 Carrots
  // (Shortcut for event.recipes.minecraft.smelting)
  event.smelting('2x minecraft:carrot', 'minecraft:golden_apple')
  // Similar recipe to above but this time it has a custom, static ID - normally IDs are auto-generated and will change. Useful for Patchouli
  event.smelting('minecraft:golden_apple', 'minecraft:carrot').id('mymodpack:my_recipe_id')

  // Add similar recipes for Blast Furnace, Smoker and Campfire
  event.blasting('3x minecraft:apple', 'minecraft:golden_apple')
  event.smoking('5x minecraft:apple', 'minecraft:golden_apple')
  event.campfireCooking('8x minecraft:apple', 'minecraft:golden_apple')
  // You can also add .xp(1.0) at end of any smelting recipe to change given XP
  
  // Add a smithing recipe that combines 2 items into one (in this case apple and gold ingot into golden apple)
  event.smithing('minecraft:golden_apple', 'minecraft:apple', 'minecraft:gold_ingot')

  // Create a function and use that to make things shorter. You can combine multiple actions
  let multiSmelt = (output, input, includeBlasting) => {
    event.smelting(output, input)
    
    if (includeBlasting) {
      event.blasting(output, input)
    }
  }
  
  multiSmelt('minecraft:blue_dye', '#forge:gems/lapis', true)
  multiSmelt('minecraft:black_dye', 'minecraft:ink_sac', true)
  multiSmelt('minecraft:white_dye', 'minecraft:bone_meal', false)

  // If you use custom({json}) it will be using vanilla Json/datapack syntax. Must include "type": "mod:recipe_id"!
  // You can add recipe to any recipe handler that uses vanilla recipe system or isn't supported by KubeJS
  // You can copy-paste the json directly, but you can also make more javascript-y by removing quotation marks from keys
  // You can replace {item: 'x', count: 4} in result fields with Item.of('x', 4).toResultJson()
  // You can replace {item: 'x'} / {tag: 'x'} with Ingredient.of('x').toJson() or Ingredient.of('#x').toJson()
  // In this case, add Create's crushing recipe, Oak Sapling to Apple + 50% Carrot
  
  // Important! Create has integration already, so you don't need to use this. This is just an example for datapack recipes!
  // Note that not all mods format their jsons the same, often the key names ('ingredients', 'results', ect) are different. 
  // You should check inside the mod jar (mod.jar/data/modid/recipes/) for examples
  event.custom({
    type: 'create:crushing',
    ingredients: [
      Ingredient.of('minecraft:oak_sapling').toJson()
    ],
    results: [
      Item.of('minecraft:apple').toResultJson(),
      Item.of('minecraft:carrot').withChance(0.5).toResultJson()
    ],
    processingTime: 100
  })
  
  // Example of using items with NBT in a recipe
  event.shaped('minecraft:book', [
    'CCC',
    'WGL',
    'CCC'
  ], {
    C: '#forge:cobblestone',
    // Item.of('id', '{key: value}'), it's recommended to use /kubejs hand
    // If you want to add a count its Item.of('id', count, '{key: value}'). This won't work here though as crafting table recipes to do accept stacked items
    L: Item.of('minecraft:enchanted_book', '{StoredEnchantments:[{lvl:1,id:"minecraft:sweeping"}]}'),
    // Same principle, but if its an enchantment, there's a helper method
    W: Item.of('minecraft:enchanted_book').enchant('minecraft:respiration', 2),
    G: '#forge:glass'
  })
  
  // In all shapeless crafting recipes, replace any planks with Gold Nugget in input items
  event.replaceInput({type: 'minecraft:crafting_shapeless'}, '#minecraft:planks', 'minecraft:gold_nugget')
  
  // In all recipes, replace Stick with Oak Sapling in output items 
  event.replaceOutput({}, 'minecraft:stick', 'minecraft:oak_sapling')
  
  // By default KubeJS will mirror and shrink recipes, which makes things like UU-Matter crafting (from ic2) harder to do as you have less shapes.
  // You can use noMirror() and noShrink() to stop this behaviour.
  event.shaped('9x minecraft:emerald', [
    ' D ',
    'D  ',
    '   '
  ], {
    D: 'minecraft:diamond'
  }).noMirror().noShrink()
})

Possible settings you can change for recipes. It's recommended that you put this in it's own server scripts file, like settings.js

// priority: 5

// Enable recipe logging, off by default
settings.logAddedRecipes = true
settings.logRemovedRecipes = true
// Enable skipped recipe logging, off by default
settings.logSkippedRecipes = true
// Enable erroring recipe logging, on by default, recommended to be kept to true
settings.logErroringRecipes = false

As mentioned before, you can add any recipe from any mod with JSON syntax (see event.custom({})) but these mods are supported as addons with special syntax:


Ingredient Actions

Poorly documented things below!

You can transform ingredients in shaped and shapeless recipes by adding these functions at end of it:

IngredientFilter can be either

Examples:

onEvent('recipes', event => {
  	event.shapeless('9x minecraft:melon_slice', [ // Craft 9 watermelon slices
		Item.of('minecraft:diamond_sword').ignoreNBT(), // Diamond sword that ignores damage
		'minecraft:melon' // Watermelon block
	]).damageIngredient(Item.of('minecraft:diamond_sword').ignoreNBT()) // Damage the sword (also has to ignore damage or only 0 damage will work)
  
    // Craft example block from 2 diamond swords and 2 dirt. After crafting first diamond sword is damaged (index 0) and 2nd sword is kept without changes.
	event.shaped('kubejs:example_block', [
		'SD ',
		'D S'
	], {
		S: Item.of('minecraft:diamond_sword').ignoreNBT(),
		D: 'minecraft:dirt'
	}).damageIngredient(0).keepIngredient('minecraft:diamond_sword')

    // Craft example block from 2 diamond swords and 2 stones. After crafting, diamond sword is replaced with stone sword
	event.shapeless('kubejs:example_block', [
		Item.of('minecraft:diamond_sword').ignoreNBT(),
		'minecraft:stone',
		Item.of('minecraft:diamond_sword').ignoreNBT(),
		'minecraft:stone'
	]).replaceIngredient('minecraft:diamond_sword', 'minecraft:stone_sword')

    // Craft clay from sand, bone meal, dirt and water bottle. After crafting, glass bottle is left in place of water bottle
	event.shapeless('minecraft:clay', [
		'minecraft:sand',
		'minecraft:bone_meal',
		'minecraft:dirt',
		Item.of('minecraft:potion', {Potion: "minecraft:water"})
	]).replaceIngredient({item: Item.of('minecraft:potion', {Potion: "minecraft:water"})}, 'minecraft:glass_bottle')
  
  	// Register a customIngredientAction, and recipe that uses it
  	// This one takes the nbt from an enchanted book and applies it to a tool in the crafting table, for no cost.
  	// Thanks to Prunoideae for providing it!
  	Ingredient.registerCustomIngredientAction("apply_enchantment", (itemstack, index, inventory) => {
        let enchantment = inventory.get(inventory.find(Item.of("minecraft:enchanted_book").ignoreNBT())).nbt;
        if (itemstack.nbt == null)
            itemstack.nbt = {}
        itemstack.nbt = itemstack.nbt.merge({ Enchantments: enchantment.get("StoredEnchantments") })
        return itemstack;
    })
  
 	event.shapeless("minecraft:book", ["#forge:tools", Item.of("minecraft:enchanted_book").ignoreNBT()])
        .customIngredientAction("#forge:tools", "apply_enchantment")
})

Item Modification

item.modification event is a startup script event that allows you to change properties of existing items

onEvent('item.modification', event => {
  event.modify('minecraft:ender_pearl', item => {
    item.maxStackSize = 64
    item.fireResistant = true
  })
})

All available properties:

WorldgenAddEventJS (1.16)

This event isn't complete yet and can only do basic things. Adding dimension-specific features also isn't possible yet, but is planned.

Example script: (kubejs/startup_scripts/worldgen.js)

onEvent('worldgen.add', event => {
  event.addLake(lake => { // Create new lake feature
    lake.block = 'minecraft:diamond_block' // Block ID (Use [] syntax for properties)
    lake.chance = 3 // Spawns every ~3 chunks
  })

  event.addOre(ore => {
    ore.block = 'minecraft:glowstone' // Block ID (Use [] syntax for properties)
    ore.spawnsIn.blacklist = false // Inverts spawn whitelist
    ore.spawnsIn.values = [ // List of valid block IDs or tags that the ore can spawn in
      '#minecraft:base_stone_overworld' // Default behavior - ores spawn in all stone types
    ]
    
    ore.biomes.blacklist = true // Inverts biome whitelist
    ore.biomes.values = [ // Biomes this ore can spawn in
      'minecraft:plains', // Biome ID
      '#nether' // OR #category, see list of categories below
    ]
    
    ore.clusterMinSize = 5 // Min blocks per cluster (currently ignored, will be implemented later, it's always 1)
    ore.clusterMaxSize = 9 // Max blocks per cluster
    ore.clusterCount = 30 // Clusters per chunk
    ore.minHeight = 0 // Min Y ore spawns in
    ore.maxHeight = 64 // Max Y ore spawns in
    ore.squared = true // Adds random value to X and Z between 0 and 16. Recommended to be true
    // ore.chance = 4 // Spawns the ore every ~4 chunks. You usually combine this with clusterCount = 1 for rare ores
  })
  
  event.addSpawn(spawn => { // Create new entity spawn
    spawn.category = 'creature' // Category, can be one of 'creature', 'monster', 'ambient', 'water_creature' or 'water_ambient'
    spawn.entity = 'minecraft:pig' // Entity ID
    spawn.weight = 10 // Weight
    spawn.minCount = 4 // Min entities per group
    spawn.maxCount = 4 // Max entities per group
  })
})

All values are optional. All feature types have biomes field like addOre example

Valid biome categories ('#category'):

You can also use ('$type' (case doesn't matter)) on Forge's BiomeDictionary:

This is the order vanilla worldgen happens:

  1. raw_generation
  2. lakes
  3. local_modifications
  4. underground_structures
  5. surface_structures
  6. strongholds
  7. underground_ores
  8. underground_decoration
  9. vegetal_decoration
  10. top_layer_modification

It's possible you may not be able to generate some things in their layer, like ores in dirt, because dirt hasn't spawned yet. So you may have to change the layer by calling ore.worldgenLayer = 'top_layer_modification'. But this is not recommended.

If you want to remove things, see this event.

Block Modification

block.modification event is a startup script event that allows you to change properties of existing blocks

onEvent('block.modification', event => {
  event.modify('minecraft:stone', block => {
    block.destroySpeed = 0.1
    block.hasCollision = false
  })
})

All available properties:

JEI Integration

All JEI events are client sided and so go in the client_scripts folder

Sub-types

onEvent('jei.subtypes', event => {
  event.useNBT('example:item')
  event.useNBTKey('example:item', 'type')
})

Hide Items & Fluids

onEvent('jei.hide.items', event => {
  event.hide('example:ingredient')
})

onEvent('jei.hide.fluids', event => {
  event.hide('example:fluid')
})

Add Items & Fluids

onEvent('jei.add.items', event => {
  event.add(Item.of('example:item', {test: 123}))
})

onEvent('jei.add.fluids', event => {
  event.add('example:fluid')
})

Add Information

onEvent('jei.information', event => {
  event.add('example:ingredient', ['Line 1', 'Line 2'])
})

Hide categories

onEvent('jei.remove.categories', event => {
  console.log(event.getCategoryIds()) //log a list of all category ids to logs/kubejs/client.txt
  
  event.remove('create:compacting')
})

WorldgenRemoveEventJS (1.16)

For more information on biomes field, see worldgen.add event page.

onEvent('worldgen.remove', event => {
  event.removeOres(ores => {
    ores.blocks = [ 'minecraft:coal_ore', 'minecraft:iron_ore' ] // Removes coal and iron ore
    ores.biomes.values = [ 'minecraft:plains' ] // Removes it only from plains biomes
  })
  
  event.removeSpawnsByID(spawns => {
    spawns.entities.values = [
      'minecraft:cow',
      'minecraft:chicken',
      'minecraft:pig',
      'minecraft:zombie'
    ]
  })
  
  event.removeSpawnsByCategory(spawns => {
    spawns.biomes.values = [
      'minecraft:plains'
    ]
    spawns.categories.values = [
      'monster'
    ]
  })
})

If something isn't removing, you may try to remove it "manually" by first printing all features (this will spam your console a lot, I suggest reading logs/kubejs/startup.txt) and then removing them by ID where possible.

onEvent('worldgen.remove', event => {
  // May be one of the decoration types/levels described in worldgen.add docs
  // But ores are *most likely* to be generated in this one
  event.printFeatures('underground_ores')
})
onEvent('worldgen.remove', event => {
  event.removeFeatureById('underground_ores', 'mekanism:ore_copper')
})

REI Integration

Note: REI integration only works on Fabric in 1.16. In 1.18+, it works on both Forge and Fabric!

All REI events are client sided and so go in the client_scripts folder

For 1.19+, see below (this is a temporary page!)

Hide Items

onEvent('rei.hide.items', event => {
  event.hide('example:ingredient')
})

Add Items

onEvent('rei.add.items', event => {
  event.add(Item.of('example:item', { test: 123 })
})

Add Information

onEvent('rei.information', event => {
  event.add('example:ingredient', 'Title', ['Line 1', 'Line 2'])
})

Yeet categories

onEvent('rei.remove.categories', event => {
  console.log(event.getCategoryIds()) //log a list of all category ids to logs/kubejs/client.txt
  
  //event.remove works too, but yeeting is so much more fun 😉
  event.yeet('create:compacting')
})

Grouping / Collapsible Entries (1.18.2+)

onEvent('rei.group', event => {
  // This event allows you to add custom entry groups to REI, which can be used to clean up the entry list significantly.
  // As a simple example, we can add a 'Swords' group which will contain all (vanilla) swords
  // Note that each group will need an id (ResourceLocation) and a display name (Component / String)
  event.groupItems('kubejs:rei_groups/swords', 'Swords', [
    'minecraft:wooden_sword',
    'minecraft:stone_sword',
    'minecraft:iron_sword',
    'minecraft:diamond_sword',
    'minecraft:golden_sword',
    'minecraft:netherite_sword'
  ])

  // An easy use case for grouping stuff together could be using tags:
  // In this case, we want all the Hanging Signs and Sign Posts from Supplementaries to be grouped together
  event.groupItemsByTag('supplementaries:rei_groups/hanging_signs', 'Hanging Signs', 'supplementaries:hanging_signs')
  event.groupItemsByTag('supplementaries:rei_groups/sign_posts', 'Sign Posts', 'supplementaries:sign_posts')

  // Another example: We want all of these items to be grouped together ignoring NBT,
  // so you don't have a bajillion potions and enchanted books cluttering up REI anymore
  const useNbt = ['potion', 'enchanted_book', 'splash_potion', 'tipped_arrow', 'lingering_potion']

  useNbt.forEach(id => {
    const item = Item.of(id)
    const { namespace, path } = Utils.id(item.id)
    event.groupSameItem(`kubejs:rei_groups/${namespace}/${path}`, item.name, item)
  })

  // Items can also be grouped using anything that can be expressed as an IngredientJS,
  // including for example regular expressions or lists of ingredients
  event.groupItems('kubejs:rei_groups/spawn_eggs', 'Spawn Eggs', [
    /spawn_egg/,
    /^ars_nouveau:.*_se$/,
    'supplementaries:red_merchant_spawn_egg'
  ])

  // you can even use custom predicates for grouping, like so:
  event.groupItemsIf('kubejs:rei_groups/looting_stuff', 'Stuff with Looting I', item =>
    // this would group together all items that have the Looting I enchantment on them
    item.hasEnchantment('minecraft:looting', 1)
  )

  // you can also group fluids in much the same way as you can group items, for instance:
  event.groupFluidsByTag('kubejs:rei_groups/fluid_tagged_as_water', '\'Water\' (yeah right lmao)', 'minecraft:water')
})

This below code is meant for 1.19+

Hide Items

REIEvents.hide('item', event => {
  event.hide('example:ingredient')
})

Add Items

REIEvents.add('item', event => {
  event.add(Item.of('example:item', { test: 123 })
})

Add Information

REIEvents.information(event => {
  event.addItem('example:ingredient', 'Title', ['Line 1', 'Line 2'])
})

Yeet categories

REIEvents.removeCategories(event => {
  console.log(event.getCategoryIds()) //log a list of all category ids to logs/kubejs/client.txt
  
  //event.remove works too, but yeeting is so much more fun 😉
  event.yeet('create:compacting')
})

Grouping / Collapsible Entries (1.18.2+)

REIEvents.groupEntries(event => {
  // This event allows you to add custom entry groups to REI, which can be used to clean up the entry list significantly.
  // As a simple example, we can add a 'Swords' group which will contain all (vanilla) swords
  // Note that each group will need an id (ResourceLocation) and a display name (Component / String)
  event.groupItems('kubejs:rei_groups/swords', 'Swords', [
    'minecraft:wooden_sword',
    'minecraft:stone_sword',
    'minecraft:iron_sword',
    'minecraft:diamond_sword',
    'minecraft:golden_sword',
    'minecraft:netherite_sword'
  ])

  // An easy use case for grouping stuff together could be using tags:
  // In this case, we want all the Hanging Signs and Sign Posts from Supplementaries to be grouped together
  event.groupItemsByTag('supplementaries:rei_groups/hanging_signs', 'Hanging Signs', 'supplementaries:hanging_signs')
  event.groupItemsByTag('supplementaries:rei_groups/sign_posts', 'Sign Posts', 'supplementaries:sign_posts')

  // Another example: We want all of these items to be grouped together ignoring NBT,
  // so you don't have a bajillion potions and enchanted books cluttering up REI anymore
  const useNbt = ['potion', 'enchanted_book', 'splash_potion', 'tipped_arrow', 'lingering_potion']

  useNbt.forEach(id => {
    const item = Item.of(id)
    const { namespace, path } = Utils.id(item.id)
    event.groupSameItem(`kubejs:rei_groups/${namespace}/${path}`, item.name, item)
  })

  // Items can also be grouped using anything that can be expressed as an IngredientJS,
  // including for example regular expressions or lists of ingredients
  event.groupItems('kubejs:rei_groups/spawn_eggs', 'Spawn Eggs', [
    /spawn_egg/,
    /^ars_nouveau:.*_se$/,
    'supplementaries:red_merchant_spawn_egg'
  ])

  // you can even use custom predicates for grouping, like so:
  event.groupItemsIf('kubejs:rei_groups/looting_stuff', 'Stuff with Looting I', item =>
    // this would group together all items that have the Looting I enchantment on them
    item.hasEnchantment('minecraft:looting', 1)
  )

  // you can also group fluids in much the same way as you can group items, for instance:
  event.groupFluidsByTag('kubejs:rei_groups/fluid_tagged_as_water', '\'Water\' (yeah right lmao)', 'minecraft:water')
})

ItemTooltipEventJS

A client event that allows adding tooltips to any item!

onEvent('item.tooltip', tooltip => {
  // Add tooltip to all of these items
  tooltip.add(['quark:backpack', 'quark:magnet', 'quark:crate'], 'Added by Quark Oddities')
  // You can also use any ingredient except #tag (due to tags loading much later than client scripts)
  tooltip.add(/refinedstorage:red_/, 'Can be any color')
  // Multiple lines with an array []. You can also escape ' by using other type of quotation marks
  tooltip.add('thermal:latex_bucket', ["Not equivalent to Industrial Foregoing's Latex", 'Line 2 text would go here'])
  // Use some data from the client to decorate this tooltip. name returns a component so we just append that.
  tooltip.add('minecraft:skeleton_skull', Text.of('This used to be ').append(Client.player.name).append("'s head"))
  
  tooltip.addAdvanced('thermal:latex_bucket', (item, advanced, text) => {
    text.add(0, Text.of('Hello')) // Adds text in first line, pushing the items name down a line. If you want the line below the item name, the index must be 1
  })
  
  tooltip.addAdvanced('minecraft:beacon', (item, advanced, text) => {
    // shift, alt and ctrl are all keys you can check!
    if (!tooltip.shift) {
      text.add(1, [Text.of('Hold ').gold(), Text.of('Shift ').yellow(), Text.of('to see more info.').gold()])
    } else {
      text.add(1, Text.green('Gives positive effects to players in a range').bold(true))
      text.add(2, Text.red('Requires a base built out of precious metals or gems to function!'))
      text.add(3, [Text.white('Iron, '), Text.aqua('Diamonds, '), Text.gold('Gold '), Text.white('or even '), Text.green('Emeralds '), Text.white('are valid base blocks!')])
    }
  })
  
  // Neat utility to display NBT in the tooltip
  tooltip.addAdvanced(Ingredient.all, (item, advanced, text) => {
    if (tooltip.alt && item.nbt) {
      text.add(Text.of('NBT: ').append(Text.prettyPrintNbt(item.nbt)))
    }
  })
  
  // Show the name of the player who owns the skull in a skulls tooltip
  tooltip.addAdvanced('minecraft:player_head', (item, advanced, text) => {
    let playername = item.nbt?.SkullOwner?.Name
    if (playername) {
      text.add(Text.red(`The head of ${playername}`))
    }
  })
})

Worldgen Events

These following examples will only work on 1.18+! If you need examples for 1.16, you can look here if you want to add new features to world generation and here if you want to remove features from it.

General Notes

Biome Filters:

Biome filters work similarly to recipe filters, and can be used to create complex and exact filters to fine tune exactly where your features may and may not spawn in the world. They are used for the biomes field of a feature and may look something like this:

onEvent('worldgen.add', event => {
  event.addOre(ore => {
    // let's look at all of the 'simple' filters first
    ore.biomes = 'minecraft:plains' 		// only spawn in exactly this biome
    ore.biomes = /^minecraft:.*/			// spawn in all biomes that match the given pattern (here: anything that starts with minecraft:)
    ore.biomes = '#minecraft:is_forest' 	// [1.19+] spawn in all biomes tagged as 'minecraft:is_forest'
    ore.biomes = '^nether' 				// [1.18 only!] spawn in all biomes in the 'nether' category (see Biome Categories)
    ore.biomes = '$hot'					// [Forge 1.18 only!] spawn in all biomes that have the 'hot' biome type (see Biome Dictionary)
    // filters can be arbitrarily combined using AND, OR and NOT logic
    ore.biomes = {}						// empty AND filter, always true
    ore.biomes = []						// empty OR filter, also always true
    ore.biomes = {
      not: 'minecraft:ocean'				// spawn in all biomes that are NOT 'minecaraft:ocean'
    }
    // since AND filters are expressed as maps and expect string keys,
    // all of the 'primitive' filters can also be expressed as such
    ore.biomes = {					// see above for an explanation of these filters
      id: 'minecraft:plains',
      id: /^minecraft:.*/,			// regex (also technically an id filter)
      tag: '#minecraft:is_forest',
      category: '^nether',
      biome_type: '$hot',
    }
    // note all of the above syntax may be mixed and matched individually
    // for example, this will spawn the feature in any biome that is
    // either plains, or a hot biome that is not in the nether or savanna categories
    ore.biomes = [
      'minecraft:plains', {
        biome_type: '$hot',
        not: [
          '#nether',
          { category: 'savanna' }
        ]
      },
    ]
  })
})


Rule Tests and Targets:

In 1.18, Minecraft worldgen has changed to a "target"-based replacement system, meaning you can specify specific blocks to be replaced with specific other blocks within the same feature configuration. (This is used to replace stone with the normal ore and deepslate with the deepslate ore variant, for example).

Each target gets a "rule test" as input (something that checks if a given block state should be replaced or not) and produces a specific output block state. On the KubeJS script side, both of these concepts are expressed as the same class: BlockStatePredicate.

Syntax-wise, BlockStatePredicate is pretty similar to biome filters as they too can be combined using AND or OR filters (which is why we will not be repeating that step here), and can be used to match one of three different things fundamentally:

  1. Blocks (these are simply parsed as strings, so for example "minecraft:stone" to match Stone)
  2. Block States (these are parsed as the block id followed by an array of properties, so you would use something like "minecraft:furnace[lit=true]" to match only furnace blocks that are active (lit). You can use F3 to figure out a block's properties, as well as possible values through using the debug stick.
  3. Block Tags (as you might expect, these are parsed in the "familiar" tag syntax, so you could for example use "#minecraft:base_stone_overworld" to match all types of stone that can be found generating in the ground in the overworld. Note that these are block tags, not item tags, so they may (and probably will) be different! (F3 is your friend!)

You can also use regular expressions with block filters, so /^mekanism:.*_ore$/ would match any block from Mekanism whose id ends with "_ore". Keep in mind this will not match block state properties!

When a RuleTest is required instead of a BlockStatePredicate, you can also supply that rule test directly in the form of a JavaScript object (it will then be parsed the same as vanilla would parse JSON or NBT objects). This can be useful if you want rule tests that have a random chance to match, for example!

More examples on how targets work can be found in the example script down below.

Height Providers:

Another system that may appear a bit confusing at first is the system of "height providers", which are used to determine at what Y level a given ore should spawn and with what frequency. Used in tandem with this feature are the so-called "vertical anchors", which may be used to get the height of something relative to a specific anchor point (for example the top or bottom of the world)

In KubeJS, this system has been simplified a bit to make it easier to use for script developers: To use the two most common types of ore placement, uniform (the feature has the same chance to spawn anywhere in between the two anchors) and triangle (the feature is more likely to spawn in the center of the two anchors than it is to spawn further outwards), you can use the methods uniformHeight and traingleHeight in AddOreProperties, respectively. Vertical anchors have also been simplified, as you can use the aboveBottom / belowTop helper methods in AddOreProperties, or, in newer KubeJS versions, the builtin class wrapper for VerticalAnchor (Note that the former has been deprecated in favour of the latter), as well as if you want to specify absolute heights as simple numbers, instead.

Once again, see the example script for more information!

(1.18 only!) Biome Categories:

Biome categories are a vanilla system that can be used to roughly sort biomes into predefined categories, which are noted below. Note that other mods may add more categories through extending the enum, however since there is no way for us to know this we will only provide you with the vanilla IDs here:

(1.18 and Forge only!) Biome Dictionary:

Much like Vanilla biome categories, Forge uses a "Biome Dictionary" to sort biomes based on their properties. Note that this system is designed to be extended by mods, so there is no way for us to give a complete list of all categories to you, however some of the ones you might commonly find yourself using are listed here:

In 1.19, both of these systems have been removed with no replacement in favour of biome tags!

Example script: (kubejs/startup_scripts/worldgen.js)

onEvent('worldgen.add', event => {
  // use the anchors helper from the event (NOTE: this requires newer versions of KubeJS)
  // if you are using an older version of KubeJS, you can use the methods in the ore properties class
  const { anchors } = event

  event.addOre(ore => {
    ore.id = 'kubejs:glowstone_test_lmao' // (optional, but recommended) custom id for the feature
    ore.biomes = {
      not: '^savanna' // biome filter, see above (technically also optional)
    }

    // examples on how to use targets
    ore.addTarget('#minecraft:stone_ore_replaceables', 'minecraft:glowstone') // replace anything in the vanilla stone_ore_replaceables tag with Glowstone
    ore.addTarget('minecraft:deepslate', 'minecraft:nether_wart_block')       // replace Deepslate with Nether Wart Blocks
    ore.addTarget([
      'minecraft:gravel',     // replace gravel...
      /minecraft:(.*)_dirt/   // or any kind of dirt (including coarse, rooted, etc.)...
    ], 'minecraft:tnt')       // with TNT (trust me, it'll be funny)

    ore.count([15, 50])             // generate between 15 and 50 veins (chosen at random), you could use a single number here for a fixed amount of blocks
      .squared()                    // randomly spreads the ores out across the chunk, instead of generating them in a column
      .triangleHeight(				      // generate the ore with a triangular distribution, this means it will be more likely to be placed closer to the center of the anchors
        anchors.aboveBottom(32),    // the lower bound should be 32 blocks above the bottom of the world, so in this case, Y = -32 since minY = -64
        anchors.absolute(96)	      // the upper bound, meanwhile is set to be just exactly at Y = 96
      )								              // in total, the ore can be found between Y levels -32 and 96, and will be most likely at Y = (96 + -32) / 2 = 32

    // more, optional parameters (default values are shown here)
    ore.size = 9                            // max. vein size
    ore.noSurface = 0.5                     // chance to discard if the ore would be exposed to air
    ore.worldgenLayer = 'underground_ores'  // what generation step the ores should be generated in (see below)
    ore.chance = 0							// if != 0 and count is unset, the ore has a 1/n chance to generate per chunk
  })

  // oh yeah, and did I mention lakes exist, too?
  // (for now at least, Vanilla is likely to remove them in the future)
  event.addLake(lake => {
    lake.id = 'kubejs:funny_lake' // BlockStatePredicate
    lake.chance = 4
    lake.fluid = 'minecraft:lava'
    lake.barrier = 'minecraft:diamond_block'
  })
})

onEvent('worldgen.remove', event => {
  console.info('HELP')
  //console.debugEnabled = true;

  // print all features for a given biome filter
  event.printFeatures('', 'minecraft:plains')

  event.removeOres(props => {
    // much like ADDING ores, this supports filtering by worldgen layer...
    props.worldgenLayer = 'underground_ores'
    // ...and by biome
    props.biomes = [
      { category: 'icy' },
      { category: 'savanna' },
      { category: 'mesa' }
    ]

    // BlockStatePredicate to remove iron and copper ores from the given biomes
    // Note tags may NOT be used here, unfortunately...
    props.blocks = ['minecraft:iron_ore', 'minecraft:copper_ore']
  })

  // remove features by their id (first argument is a generation step)
  event.removeFeatureById('underground_ores', ['minecraft:ore_coal_upper', 'minecraft:ore_coal_lower'])
})

Generation Steps

  1. raw_generation
  2. lakes
  3. local_modifications
  4. underground_structures
  5. surface_structures
  6. strongholds
  7. underground_ores
  8. underground_decoration
  9. vegetal_decoration
  10. top_layer_modification

It's possible you may not be able to generate some things in their layer, like ores in dirt, because dirt hasn't spawned yet. So you may have to change the layer to one of the above generation steps by calling ore.worldgenLayer = 'top_layer_modification'. This is, however, not recommended.

Chat Event

This script is peak of human evolution. Whenever someone says "Creeper" in chat, it replies with "Aw man".

onEvent('player.chat', (event) => {
  // Check if message equals creeper, ignoring case
  if (event.message.trim().equalsIgnoreCase('creeper')) {
    // Schedule task in 1 tick, because if you reply immidiently, it will print before player's message
    event.server.scheduleInTicks(1, event.server, (callback) => {
      // Tell everyone Aw man, colored green. Callback data is the server
      callback.data.tell(Text.green('Aw man'))
    })
  }
})

Another example, cancelling the chat event. No need to schedule anything now, because player's message wont be printed,

onEvent('player.chat', (event) => {
  // Check if message equals creeper, ignoring case
  if (event.message.startsWith('!some_command')) {
    event.player.tell('Hi!')
    event.cancel()
  }
})

Custom Fluids

Supported by Forge on all versions, and Fabric on 1.18.2+

// Startup script
onEvent('fluid.registry', event => {
  // These first examples are 1.16.5 and 1.18.2 syntax
  
  // Basic "thick" (looks like lava) fluid with red tint
  event.create('thick_fluid')
    .thickTexture(0xFF0000)
    .bucketColor(0xFF0000)
    .displayName('Thick Fluid')
               
  // Basic "thin" (looks like water) fluid with cyan tint, has no bucket and is not placeable
  event.create('thick_fluid')
    .thinTexture(0xFF0000)
    .bucketColor(0x00FFFF)
    .displayName('Thin Fluid')
  	.noBucket() // both these methods are 1.18.2+ only
  	.noBlock() 
  
  // Fluid with custom textures
  event.create('strawberry_cream')
  	.displayName('Strawberry Cream')
    .stillTexture('kubejs:block/strawberry_still')
    .flowingTexture('kubejs:block/strawberry_flow')
    .bucketColor(0xFF33FF)
  
  // For 1.18.1 the syntax is slightly different
  event.create('thick_fluid', fluid => {
       fluid.textureThick(0xFF0000) // the texture method names are different in 1.18.1 and below, textureXyz instead of xyzTexture
       fluid.bucketColor(0xFF0000)
       fluid.displayName('Thick Fluid')
  })
})

In 1.18.1, 1.17 and 1.16 the texture method names are swapped, so textureStill and textureThin instead of stillTexture and thinTexture

Methods that you can use after the event.create('name')

The following can also be used but have no effect unless a mod adds a purpose:

There is a good chance the following does not work at all

You can use .bucketItem to get the bucket item builder.

If you one want to use it then you can place it at the end of the other methods then use the its methods instead.

// notice this script has not been tested
onEvent('fluid.registry', event => {
  event.create('taco_suace')
                .thickTexture(0xFF0000)
                .bucketColor(0xFF0000)
                .bucketItem
                .group("food")
})

Some amount of the methods in these builders will not work or cause problems


Command Registry

This page is unfinished and only provides basic information

Example:

The following code has not been completely tested on 1.18 and not at all on 1.16

onEvent("command.registry", event => {//command registry event
    const { commands: Commands, arguments: Arguments} = event;
    event.register(//register a new command
        Commands.literal("myCommand")//the command is called myCommand
		.requires(src => src.hasPermission(2))//2 is op. This line is optional, but you can also instead of just one value, wrap it in {}s and use return to write a more complex requirement checks
		.then(Commands.argument('arg1', Arguments.STRING.create(event))//takes argument string called arg1. You can have as many (or none) as you want.
			.then(Commands.argument('arg2', Arguments.FLOAT.create(event))//takes argument float called arg2. The other type you can use can be found with ProbeJS
				.executes(ctx => {//run the command
					const arg1 = Arguments.STRING.getResult(ctx, "arg1");//get recipe
					const arg2 = Arguments.FLOAT.getResult(ctx, "arg2");//get the value
                    //your code goes here
					if(arg1 == "example")
                    	return 0//return 0 means command did not work
                    let level = ctx.source.level.asKJS()
                    let position = ctx.source.position
                    //hurt entities in a around a area of where the command was run
                    let i = 0
                    level.getEntitiesWithin(AABB.of(position.x()-2,position.y()-2,position.z()-2,position.x()+2,position.y()+2,position.z()+2)).forEach(entity => {
                    	if (entity.living) {
                          entity.attack(arg2)
                          i++
                          if (entity.type == "minecraft:player") entity.tell(arg1) //tell players that got hurt the message that is arg1
                        }
                    })
					return i // always return something
				})
			)// every then requires a ')' so dont forget them
		)//but requires does not
    )
})

Datapack Load Events

You can load json datapack files programmatically!

onEvent('server.datapack.first', event => {
		event.addJson(name, json)
})

resourceLocation could be minecraft:loot_tables/entities/villager.json

json could be for example:

{
  type: "entity",
  pools: [
    {
      rolls: 2,
      bonus_rolls: 1,
      entries: [
        {
          type: "item",
          weight: 3,
          name: "minecraft:emerald"
        },
        {
          type: "empty",
          weight: 2
        }
      ]
    }
  ]
}

Note: Practically everything in vanilla has a way better to programmatically load it, so it is recommended to use this mostly for loading thing for other mods

There are different timing that you can make the file get loaded too!

This event is useful, because instead of needing to write multiple json files, you can write one then change the values passed to it.

Example

Adds multiple advancements for using different items that reward experience:

onEvent('server.datapack.first', event => {
  	const items = ['bow', 'golden_hoe', 'flint_and_steel', 'spyglass']
    items.forEach(item => {
		event.addJson(`kubejs:advancements/${item}`, {
			criteria: {
				requirement: {
					trigger: "minecraft:using_item",
					conditions: {
						item: {
							items: [`minecraft:${item}`]
						}
					}
				}
			},
			rewards: {
				experience: 20
			}
		})
	})
})

In the custom machinery mod, the packdev needs to make a massive json file for each machine they wish to create. This script will make 16 machines, and is shorter then even a single on of the original json files would have been.

onEvent('server.datapack.first', event => {
	let json
	//create 16 custom machines with 6 inputs and 1 output
	for (let machineNumber = 0; machineNumber < 16; machineNumber++) {

		json = {
			name: {
				text: `${machineNumber}`
			},
			appearance: {},
			components: [
				{
                  "type": "custommachinery:item",
					"id": "out",
					"mode": "output"
				}
			],
			gui: [
				{
					"type": "custommachinery:progress",
					"x": 70,
					"y": 41,
					"width": 18,
					"height": 18
				},{
					"type": "custommachinery:slot",
					"x": 88,
					"y": 41,
					"id": "out"
				},{
					"type": "custommachinery:text",
					"text": `Machine ${machineNumber}`,//string builder to make the name match the machine number
					"x":16,
					"y":16
				},{
					"type": "custommachinery:texture",
					"x": 0,
					"y": 0,
					"texture": "custommachinery:textures/gui/base_background.png",
					"priority": 1000
				},{
					"type": "custommachinery:player_inventory",
					"x": 16,
					"y": 68
				}
			]
		}

		//add the input slots and corrasponding componets
		let slotNumber = 0
      	const xValues = [16,34,52]
        const yValues = [32,50]
		xValues.forEach(x => {
			yValues.forEach(y => {

				json.components.push({
					"type": "custommachinery:item",
					"id": `input${slotNumber}`,
					"mode": "input"
				})

				json.gui.push({
					"type": "custommachinery:slot",
					"x": x,
					"y": y,
					"id": `input${slotNumber}`
				})

				slotNumber++
			})
		})

		//add the json
		event.addJson(`kubejs:machines/${machineNumber}`,json)
	}
})