SCRIPTING DOCUMENTATION
Version: 1.17.10.4

Index#

Script API Objects#

Here you can find the definition of some objects returned by the script API.

Entity JS API Object#

Name	Type	Entity JS API Object	Description
__identifier__	String		READ ONLY. This is the identifier for the object in the format namespace:name. For example, if the type is entity and the object is representing a vanilla cow, the identifier would be minecraft:cow
__type__	String		READ ONLY. This defines the type of object. Can be: "entity" or "item_entity".
id	Positive Integer		READ ONLY. This is the unique identifier of the entity.

Level JS API Object#

Name	Type	Level JS API Object	Description
__type__	String		READ ONLY. This defines the type of object. Will be: "level".
level_id	Positive Integer		READ ONLY. This is the unique identifier of the level.

Component JS API Object#

Name	Type	Component JS API Object	Description
__type__	String		READ ONLY. This defines the type of object. Will be: "component".
data	JavaScript Object		This is the content of the component.

Query JS API Object#

Name	Type	Query JS API Object	Description
__type__	String		READ ONLY. This defines the type of object. Will be: "query".
query_id	Positive Integer		READ ONLY. This is the unique identifier of the query.

ItemStack JS API Object#

Name	Type	ItemStack JS API Object	Description
__identifier__	String		READ ONLY. This is the identifier for the object in the format namespace:name. For example, if the type is entity and the object is representing a vanilla cow, the identifier would be minecraft:cow
__type__	String		READ ONLY. This defines the type of object. Will be: "item_stack".
count	String		READ ONLY. This is the number of items in the stack.
item	String		READ ONLY. This is the identifier of the item.

Block JS API Object#

Name	Type	Block JS API Object	Description
__identifier__	String		READ ONLY. This is the identifier for the object in the format namespace:name. For example, if the type is block and the object is representing a block of bedrock, the identifier would be minecraft:bedrock
__type__	String		READ ONLY. This defines the type of object. Will be: "block".
block_position	JavaScript Object		READ ONLY. This is the position of the block and it functions as part of its unique identifier. Parameters# Name Type Description x Integer The x position y Integer The y position z Integer The z position
ticking_area	JavaScript Object		READ ONLY. This is the ticking area object that was used to get this block.

Ticking Area JS API Object#

Entity Ticking Area JS API Object#

Name	Type	Entity Ticking Area JS API Object	Description
__type__	String		READ ONLY. This defines the type of object. Will be: "entity_ticking_area".
entity_ticking_area_id	Positive Integer		READ ONLY. This is the unique identifier of the ticking area.

Level Ticking Area JS API Object#

Name	Type	Level Ticking Area JS API Object	Description
__type__	String		READ ONLY. This defines the type of object. Will be: "level_ticking_area".
level_ticking_area_id	String		READ ONLY. This is the unique identifier of the ticking area.

Script Bindings#

Bindings are the capabilities of the Minecraft Script Engine to change or modify things in the game.

Logging Bindings#

log(Message)#

The log function is accessed through the server or client objects and allows for logging a message to the ContentLog file. On Windows 10 devices it is located at ' %APPDATA%\..\Local\Packages\Microsoft.MinecraftUWP_8wekyb3d8bbwe\LocalState\logs '

Parameters#

Name	Type	Description
Message	String	The message that you want to send to the log file

Code Example:

Log

system.exampleFunction = function() {
  client.log("example log message") 
}; 

Entity Bindings#

createEntity()#

NOTE: Entities are created first on the server, with the client notified of new entities afterwards. Be aware that if you send the result object to the client right away, the created entity might not exist on the client yet.

Return Value#

Type	Value
Entity JS API Object	An object representing the newly created entity

createEntity(Type, TemplateIdentifier)#

NOTE: Entities are created first on the server, with the client notified of new entities afterwards. Be aware that if you send the result object to the client right away, the created entity might not exist on the client yet.

Parameters#

Name	Type	Description
TemplateIdentifier	String	This can be any of the entity identifiers from the applied Behavior Packs. For example specifying minecraft:cow here will make the provided entity a cow as defined in JSON
Type	String	Specifies the type of the entity that is being created by the template. Valid inputs are `entity` and `item_entity`

Return Value#

Type	Value
Entity JS API Object	An object representing the newly created entity

destroyEntity(EntityObject)#

Parameters#

Name	Type	Description
EntityObject	Entity JS API Object	The object that was retrieved from a call to createEntity() or retrieved from an entity event

Return Value#

Type	Value
Boolean	The entity was successfully destroyed

isValidEntity(EntityObject)#

Parameters#

Name	Type	Description
EntityObject	Entity JS API Object	The object that was retrieved from a call to createEntity() or retrieved from an entity event

Return Value#

Type	Value
Boolean	The entity is in the Script Engine's database of entities

Component Bindings#

registerComponent(ComponentIdentifier, ComponentData)#

Parameters#

Name	Type	Description
ComponentData	JavaScript Object	A JavaScript Object that defines the name of the fields and the data each field holds inside the component.
ComponentIdentifier	String	The identifier of the custom component. It is required to use a namespace so you can uniquely refer to it later without overlapping a name with a built-in component: for example 'myPack:myCustomComponent'

Return Value#

Type	Value
Boolean	The component was successfully registered

Code Example:

Registering a custom component

const mySystem = server.registerSystem(0, 0);

mySystem.initialize = function() {
  this.registerComponent("myPack:myCustomComponent", { myString: "string", myNumber: 0, myBool: true, myArray: [1, 2, 3] });
};

createComponent(EntityObject, ComponentIdentifier)#

Parameters#

Name	Type	Description
ComponentIdentifier	String	The identifier of the component to add to the entity. This is either the identifier of a built-in component (check the Script Components section) or a custom component created with a call to registerComponent()
EntityObject	Entity JS API Object	The EntityObject that was retrieved from a call to createEntity() or retrieved from an event

Return Value#

Type	Value
Component JS API Object	An object with the following fields, and additionally, all the fields as defined in the component

Code Example:

Creating a custom component

let globals = {
  ready: false
};

const mySystem = server.registerSystem(0, 0);

mySystem.initialize = function() {
  this.registerComponent("myPack:myCustomComponent", { myString: "string", myNumber: 0, myBool: true, myArray: [1, 2, 3] });
}

mySystem.update = function() {
  if(globals.ready == false) {
    globals.ready = true;
    let myEntity = this.createEntity();
    if(myEntity != null) {
      let myComponent = this.createComponent(myEntity, "myPack:myCustomComponent");
    }
  }
};

hasComponent(EntityObject, ComponentIdentifier)#

Parameters#

Name	Type	Description
ComponentIdentifier	String	The identifier of the component to check on the entity. This is either the identifier of a built-in component (check the Script Components section) or a custom component created with a call to registerComponent()
EntityObject	Entity JS API Object	The EntityObject that was retrieved from a call to createEntity() or retrieved from an event

Return Value#

Type	Value
Boolean	The EntityObject has the component

Code Example:

Check whether an entity has specified component

let globals = {
  ready: false
};

const mySystem = server.registerSystem(0, 0);

mySystem.update = function() {
  if(globals.ready == false) {
    globals.ready = true;
    let entity = this.createEntity("entity", "minecraft:pig");
    if(this.hasComponent(entity, "minecraft:nameable")) {
      // Do some work
    }
  }
};

getComponent(EntityObject, ComponentIdentifier)#

Parameters#

Name	Type	Description
ComponentIdentifier	String	The identifier of the component to retrieve from the entity. This is either the identifier of a built-in component (check the Script Components section) or a custom component created with a call to registerComponent()
EntityObject	Entity JS API Object	The EntityObject that was retrieved from a call to createEntity() or retrieved from an event

Return Value#

Type	Value
Component JS API Object	An object with the following fields, and additionally, all the fields as defined in the component Component JS API Object# Name Type Component JS API Object Description __type__ String READ ONLY. This defines the type of object. Will be: "component". data JavaScript Object This is the content of the component.

Code Example:

Get a specified component from an entity

let globals = {
  ready: false
};

const mySystem = server.registerSystem(0, 0);

mySystem.update = function() {
  if(globals.ready == false) {
    globals.ready = true;
    let entity = this.createEntity("entity", "minecraft:pig");
    let positionComponent = this.getComponent(entity, "minecraft:position");
    if (positionComponent != null) {
      positionComponent.data.x = 0;
      positionComponent.data.y = 0;
      positionComponent.data.z = 0;
    }
  }
};

applyComponentChanges(EntityObject, ComponentObject)#

Parameters#

Name	Type	Description
ComponentObject	Component JS API Object	The component object retrieved from the entity that was returned by either createComponent() or getComponent()
EntityObject	Entity JS API Object	The entity object that we are applying the component changes to

Return Value#

Type	Value
Boolean	The component was successfully updated

Code Example:

Apply updates to an entity's component

let globals = {
  pig: null
};

const mySystem = server.registerSystem(0, 0);

mySystem.update = function() {
  if(globals.pig == null) {
    globals.pig = this.createEntity("entity", "minecraft:pig");
  }
  else {
    let positionComponent = this.getComponent(globals.pig, "minecraft:position");
    positionComponent.data.y += 0.1;
    this.applyComponentChanges(globals.pig, positionComponent);
  }
};

destroyComponent(EntityObject, ComponentIdentifier)#

Parameters#

Name	Type	Description
ComponentIdentifier	String	The identifier of the component to remove from the entity. This is either the identifier of a built-in component (check the Script Components section) or a custom component created with a call to registerComponent()
EntityObject	Entity JS API Object	The EntityObject that was retrieved from a call to createEntity() or retrieved from an event

Return Value#

Type	Value
Boolean	The component was successfully removed from the entity

Code Example:

Destroy an entity's component

let globals = {
  myEntity: null
};

const mySystem = server.registerSystem(0, 0);

mySystem.initialize = function() {
  this.registerComponent("myPack:myCustomComponent", { myString: "string", myNumber: 0, myBool: true, myArray: [1, 2, 3] });
};

mySystem.update = function() {
  if(globals.myEntity == null) {
    globals.myEntity = this.createEntity();
  }
  else {
    if(this.hasComponent(globals.myEntity, "myPack:myCustomComponent")) {
      this.destroyComponent(globals.myEntity, "myPack:myCustomComponent");
    }
    else {
      this.createComponent(globals.myEntity, "myPack:myCustomComponent");
    }
  }
};

Event Bindings#

These are the bindings used to handle events. For a list of events you can react to or trigger, check the Events section of this document.

registerEventData(EventIdentifier, EventData)#

Parameters#

Name	Type	Description
EventData	JavaScript Object	The JavaScript object with the correct fields and default values for the event
EventIdentifier	String	This is the identifier of the custom event we are registering. The namespace is required and can't be set to minecraft.

Return Value#

Type	Value
Boolean	Successfully registered the event data

createEventData(EventIdentifier)#

Parameters#

Name	Type	Description
EventIdentifier	String	This is the identifier of the custom event we are registering. The namespace is required and can't be set to minecraft.

Return Value#

Type	Value
JavaScript Object	The object containing the event data

listenForEvent(EventIdentifier, CallbackObject)#

Parameters#

Name	Type	Description
CallbackObject	JavaScript Object	The JavaScript object that will get called whenever the event is broadcast
EventIdentifier	String	This is the identifier of the event to which we want to react. Can be the identifier of a built-in event or a custom one from script

Return Value#

Type	Value
Boolean	Successfully registered to listen for the event

Code Example:

Register a callback for a specified event

const mySystem = client.registerSystem(0, 0);

mySystem.initialize = function() {
  this.listenForEvent("minecraft:client_entered_world", (eventData) => this.onClientEnteredWorld(eventData));
};

mySystem.onClientEnteredWorld = function(eventData) {
  let messageData = this.createEventData("minecraft:display_chat_event");
  messageData.data.message = "Player has entered the world";
  this.broadcastEvent("minecraft:display_chat_event", messageData);
};

broadcastEvent(EventIdentifier, EventData)#

Parameters#

Name	Type	Description
EventData	JavaScript Object	The data for the event. You can create a new JavaScript Object with the parameters you want to pass in to the listener and the engine will take care of delivering the data to them
EventIdentifier	String	This is the identifier of the event we want to react to. Can be the identifier of a built-in event or a custom one from script

Return Value#

Type	Value
Boolean	Successfully broadcasted the event

Code Example:

Broadcasting an event

const mySystem = client.registerSystem(0, 0);

mySystem.initialize = function() {
  let eventData = this.createEventData("minecraft:display_chat_event");
  eventData.data.message = "Hello, World!";
  this.broadcastEvent("minecraft:display_chat_event", eventData);
};

Entity Queries#

Entity Queries are a way for you to filter for entities based on their components. Once you have registered a query, you can request all the entities that are captured by it. Entity Queries will only ever return entities that are currently active in the level. If your query extends into chunks that are not currently loaded, entities there will not be included in the query.

registerQuery()#

Allows you to register a query. A query will contain all entities that meet the filter requirement.
No filters are added by default when you register a query so it will capture all entities.

Return Value#

Type	Value
Query JS API Object	An object containing the ID of the query

Code Example:

Query Registration

const mySystem = server.registerSystem(0, 0);

mySystem.initialize = function() {
  let myQuery = this.registerQuery();
};

registerQuery(Component, ComponentField1, ComponentField2, ComponentField3)#

Allows you to register a query that will only show entities that have the given component and define which fields of that component will be used as a filter when getting the entities from the query. You can either provide just the component identifier, or the component identifier and the name of 3 properties on that component to be tested (If you do specify property names, you must specify 3).

Parameters#

Name	Type	Default Value	Description
Component	String		This is the identifier of the component that will be used to filter entities when
ComponentField1	String	"x"	This is the name of the first field of the component that we want to filter entities by. By default this is set to x.
ComponentField2	String	"y"	This is the name of the second field of the component that we want to filter entities by. By default this is set to y.
ComponentField3	String	"z"	This is the name of the third field of the component that we want to filter entities by. By default this is set to z.

Return Value#

Type	Value
Query JS API Object	An object containing the ID of the query

Code Example:

Query Registration

const mySystem = server.registerSystem(0, 0);

mySystem.initialize = function() {
  let spatialQuery = this.registerQuery("minecraft:position", "x", "y", "z");
};

addFilterToQuery(Query, ComponentIdentifier)#

Allows you to add filters to your query. The query will only contain entities that have all the components specified.
By default no filters are added. This will allow queries to capture all entities.

Parameters

Name	Type	Description
ComponentIdentifier	String	This is the identifier of the component that will be added to the filter list. Only entities that have that component will be listed in the query
Query	Query JS API Object	The object containing the ID of the query that you want to apply the filter to

Code Example:

Adding a filter to a query

let globals = {
  simpleQuery: null
};
const mySystem = server.registerSystem(0, 0);

mySystem.initialize = function() {
  globals.simpleQuery = this.registerQuery();
};

mySystem.update = function() {
  globals.simpleQuery = this.registerQuery();
  this.addFilterToQuery(globals.simpleQuery, "minecraft:explode");  let explodingEntities = this.getEntitiesFromQuery(globals.simpleQuery);
  for(var entity in explodingEntities) {
    server.log(JSON.stringify(entity));
  }
};

getEntitiesFromQuery(Query)#

Allows you to fetch the entities captured by a query.

Parameters#

Name	Type	Description
Query	Query JS API Object	This is the query you registered earlier using registerQuery()

Return Value#

Type	Value
Array	An array of EntityObjects representing the entities found within the query

Code Example:

Get a list of entities from a query

const mySystem = server.registerSystem(0, 0);

mySystem.update = function() {
  let simpleQuery = this.registerQuery();
  let allEntities = this.getEntitiesFromQuery(simpleQuery);
  for(var entity in allEntities) {
    server.log(JSON.stringify(entity));
  }
};

getEntitiesFromQuery(Query, ComponentField1_Min, ComponentField2_Min, ComponentField3_Min, ComponentField1_Max, ComponentField2_Max, ComponentField3_Max)#

Allows you to fetch the entities captured by a query that was created with a component filter built-in. The only entities that will be returned are those entities that have the component that was defined when the query was registered and that have a value in the three fields on that component that were defined in the query within the values specified in the call to getEntitiesFromQuery.

Parameters#

Name	Type	Description
ComponentField1_Max	Decimal	The maximum value that the first component field needs to be on an entity for that entity to be included in the query
ComponentField1_Min	Decimal	The minimum value that the first component field needs to be on an entity for that entity to be included in the query
ComponentField2_Max	Decimal	The maximum value that the second component field needs to be on an entity for that entity to be included in the query
ComponentField2_Min	Decimal	The minimum value that the second component field needs to be on an entity for that entity to be included in the query
ComponentField3_Max	Decimal	The maximum value that the third component field needs to be on an entity for that entity to be included in the query
ComponentField3_Min	Decimal	The minimum value that the third component field needs to be on an entity for that entity to be included in the query
Query	Query JS API Object	This is the query you created earlier using registerQuery(...)

Return Value#

Type	Value
Array	An array of EntityObjects representing the entities found within the query

Code Example:

Get a list of entities from a query

let globals = {
  spatialQuery: null
};

const mySystem = server.registerSystem(0, 0);

mySystem.initialize = function() {
  globals.spatialQuery = this.registerQuery("minecraft:position", "x", "y", "z");
};

mySystem.update = function() {
  let closeEntities = this.getEntitiesFromQuery(globals.spatialQuery, 0, 10, 0, 5, 0, 10);
  for(var entity in closeEntities) {
    server.log(JSON.stringify(entity));
  }
};

Block Bindings#

These functions define how you interact with blocks.

getBlock(Ticking Area, x, y, z)#

Allows you to get a block from the world when provided an x, y, and z position. The block must be within a ticking area.

Parameters#

Name	Type	Description
Ticking Area	Ticking Area JS API Object	The ticking area the block is in
x	Integer	The x position of the block you want
y	Integer	The y position of the block you want
z	Integer	The z position of the block you want

Return Value#

Type	Value
	object
	null

getBlock(Ticking Area, PositionObject)#

Allows you to get a block from the world when provided a JavaScript object containing a position. The block must be within a ticking area.

Parameters#

Name	Type	Description
PositionObject	JavaScript Object	A JavaScript object with the x, y, and z position of the block you want Parameters# Name Type Description x Integer The x position y Integer The y position z Integer The z position
Ticking Area	Ticking Area JS API Object	The ticking area the block is in

Return Value#

Type	Value
Block JS API Object	An object containing the block

getBlocks(Ticking Area, x min, y min, z min, x max, y max, z max)#

Allows you to get an array of blocks from the world when provided a minimum and maximum x, y, and z position. The blocks must be within a ticking area. This call can be slow if given a lot of blocks, and should be used infrequently.

Parameters#

Name	Type	Description
Ticking Area	Ticking Area JS API Object	The ticking area the blocks are in
x max	Integer	The maximum x position of the blocks you want
x min	Integer	The minimum x position of the blocks you want
y max	Integer	The maximum y position of the blocks you want
y min	Integer	The minimum y position of the blocks you want
z max	Integer	The maximum z position of the blocks you want
z min	Integer	The minimum z position of the blocks you want

Return Value#

Type	Value
	array
	null

getBlocks(Ticking Area, Minimum PositionObject, Maximum PositionObject)#

Allows you to get an array of blocks from the world when provided a minimum and maximum position. The blocks must be within a ticking area. This call can be slow if given a lot of blocks, and should be used infrequently.

Parameters#

Name	Type	Description
Maximum PositionObject	JavaScript Object	A JavaScript object with the maximum x, y, and z position of the blocks you want Parameters# Name Type Description x Integer The x position y Integer The y position z Integer The z position
Minimum PositionObject	JavaScript Object	A JavaScript object with the minimum x, y, and z position of the blocks you want Parameters# Name Type Description x Integer The x position y Integer The y position z Integer The z position
Ticking Area	Ticking Area JS API Object	The ticking area the blocks are in

Return Value#

Type	Value
Array	A 3D array of block objects. Indexs are the blocks positions relative to the min position given
	null

Slash Commands#

executeCommand(Command, Callback)#

Name	Type	Description
Callback	JSON Object	The JavaScript object that will be called after the command executes
Command	String	The slash command to run

Example

system.executeCommand("/fill ~ ~ ~ ~100 ~5 ~50 stone", (commandResultData) => this.commandCallback(commandResultData));

system.commandCallback = function (commandResultData) {
  let eventData = this.createEventData("minecraft:display_chat_event");
  if (eventData) {
    eventData.data.message = message;
    this.broadcastEvent("minecraft:display_chat_event", "Callback called! Command: " + commandResultData.command + " Data: " + JSON.stringify(commandResultData.data, null, "    ") );
  }
};

Script Components#

This is the documentation for the attributes, properties, and components available from the Minecraft Script Engine.
There are two kinds of components: server components and client components. We will go into a bit more detail on what they are in their respective sections below.
Components can be added, retrieved, updated, and removed from entities. They do not exist on their own. Currently only user-defined components can be added and removed from entities. A component must be in an entity in order to retrieve or update it.
Check the Script Engine Bindings section to see how to add, remove, retrieve, and update components. This section deals with the specific API of each component.

Level Components#

minecraft:ticking_areas#

minecraft:weather#

Name	Type	Description
do_weather_cycle	Boolean	This is the world option that determines if the vanilla weather cycle will be used
lightning_level	Decimal	A value between 0 and 1 that determines how much lightning and thunder there is
lightning_time	Integer	How long, in ticks, it will lightning and thunder for
rain_level	Decimal	A value between 0 and 1 that determains how heavy the rainfall is
rain_time	Integer	How long, in ticks, it will rain for

Server Components#

As much as possible, the API of each component matches its JSON counterpart (with some differences noted).

minecraft:armor_container#

// This example will check the players helmet armor slot for a specific item after the player attacks an entity.
system.listenForEvent("minecraft:player_attacked_entity", function(eventData) {
    // Get the players armor container
    let playerArmor = system.getComponent(eventData.data.player, "minecraft:armor_container");
    // Get the players helmet
    let playerHelmet = playerArmor.data[0];
    // Destroy the attacked entity if the player has a gold helmet equipped
    if (playerHelmet.item == "minecraft:golden_helmet") {
        system.destroyEntity(eventData.data.attacked_entity);
    }
});

minecraft:attack#

Name	Type	Default Value	Description
damage	Range [a, b]		Range of the random amount of damage the melee attack deals. A negative value can heal the entity instead of hurting it Name Type Default Value Description range_max Decimal 0.0 The maximum amount of damage the entity will deal range_min Decimal 0.0 The minimum amount of damage the entity will deal

minecraft:container#

// This example will check if a block has a container.
let block; // check getBlock API on how to access a block
let has_container = system.hasComponent(block, "minecraft:container");
if (has_container === true) {
  let container = system.getComponent(block, "minecraft:container");
  // you can now use the container to read items.

minecraft:collision_box#

Sets the width and height of the Entity's collision box.

Name	Type	Default Value	Description
height	Decimal	1.0	Height of the collision box in blocks. A negative value will be assumed to be 0.
width	Decimal	1.0	Width and Depth of the collision box in blocks. A negative value will be assumed to be 0.

minecraft:damage_sensor#

Defines what events to call when this entity is damaged by specific entities or items.

Name	Type	Default Value	Description
triggers	List		List of triggers with the events to call when taking specific kinds of damage. Name Type Default Value Description cause String none Type of damage that triggers the events. damage_modifier Decimal 0.0 A modifier that adds to/removes from the base damage from the damage cause. It does not reduce damage to less than 0. damage_multiplier Decimal 1.0 A multiplier that modifies the base damage from the damage cause. If deals_damage is true the multiplier can only reduce the damage the entity will take to a minimum of 1. deals_damage Boolean true If true, the damage dealt to the entity will take away health from it, set to false to make the entity ignore that damage. on_damage JSON Object Specifies filters for entity definitions and events. on_damage_sound_event String Defines what sound to play, if any, when the on_damage filters are met.

// This example will cause an entity (in this case, a creeper) to start exploding when the player attacks it.
// Note: the entity must have the damage_sensor component and the associated events defined in their JSON description.
this.listenForEvent("minecraft:player_attacked_entity", function(eventData) {
  let damageSensorComponent = serverSystem.getComponent(eventData.attacked_entity, "minecraft:damage_sensor");
  damageSensorComponent.data[0].on_damage = { event:"minecraft:start_exploding", filters:[{test:"has_component", operator:"==", value:"minecraft:breathable"}] };
  serverSystem.applyComponentChanges(eventData.attacked_entity, damageSensorComponent);
});

minecraft:equipment#

Sets the Equipment table to use for this Entity.

Name	Type	Default Value	Description
slot_drop_chance	List		A list of slots with the chance to drop an equipped item from that slot.
table	String		The file path to the equipment table, relative to the behavior pack's root.

minecraft:equippable#

Defines an entity's behavior for having items equipped to it.

slots#

List of slots and the item that can be equipped.

Name	Type	Default Value	Description
accepted_items	List		The list of items that can go in this slot.
interact_text	String		Text to be displayed when the entity can be equipped with this item when playing with Touch-screen controls.
item	String		Identifier of the item that can be equipped for this slot.
on_equip	String		Event to trigger when this entity is equipped with this item.
on_unequip	String		Event to trigger when this item is removed from this entity.
slot	Integer	0	The slot number of this slot.

minecraft:explode#

Defines how the entity explodes.

Name	Type	Default Value	Description
breaks_blocks	Boolean	true	If true, the explosion will destroy blocks in the explosion radius.
causes_fire	Boolean	false	If true, blocks in the explosion radius will be set on fire.
destroy_affected_by_griefing	Boolean	false	If true, whether the explosion breaks blocks is affected by the mob griefing game rule.
fire_affected_by_griefing	Boolean	false	If true, whether the explosion causes fire is affected by the mob griefing game rule.
fuse_length	Range [a, b]	[0.0, 0.0]	The range for the random amount of time the fuse will be lit before exploding, a negative value means the explosion will be immediate.
fuse_lit	Boolean	false	If true, the fuse is already lit when this component is added to the entity.
max_resistance	Decimal	3.40282e+38	A blocks explosion resistance will be capped at this value when an explosion occurs.
power	Decimal	3	The radius of the explosion in blocks and the amount of damage the explosion deals.

minecraft:hand_container#

// This example will check the players offhand slot for a specific item after the player attacks an entity.
system.listenForEvent("minecraft:player_attacked_entity", function(eventData) {
    // Get the players hand container
    let handContainer = system.getComponent(eventData.data.player, "minecraft:hand_container");
    // Get the players offhand item
    let offhandItem = handContainer.data[1];
    // Destroy the attacked entity if the player has a totem in their offhand
    if (offhandItem.item == "minecraft:totem") {
        system.destroyEntity(eventData.data.attacked_entity);
    }
});

minecraft:healable#

Defines the interactions with this entity for healing it.

Name	Type	Default Value	Description
filters	Minecraft Filter		The filter group that defines the conditions for using this item to heal the entity.
force_use	Boolean	false	Determines if item can be used regardless of entity being at full health.
items	Array		The array of items that can be used to heal this entity. Name Type Default Value Description heal_amount Integer 1 The amount of health this entity gains when fed this item. item String Item identifier that can be used to heal this entity.

minecraft:health#

Name	Type	Default Value	Description
max	Integer	10	The maximum health the entity can heal
value	Integer	1	Current health of the entity

minecraft:hotbar_container#

// This example will check the players first hotbar item slot for a specific item after the player attacks an entity.
system.listenForEvent("minecraft:player_attacked_entity", function(eventData) {
    // Get the players hotbar
    let playerHotbar = system.getComponent(eventData.data.player, "minecraft:hotbar_container");
    // Get the item at the first slot in the hotbar
    let firstHotbarSlot = playerHotbar.data[0];
    // Destroy the attacked entity if the player has an apple in their first hotbar slot
    if (firstHotbarSlot.item == "minecraft:apple") {
        system.destroyEntity(eventData.data.attacked_entity);
    }
});

minecraft:interact#

Name	Type	Default Value	Description
add_items	JSON Object		Loot table with items to add to the player's inventory upon successful interaction Name Type Default Value Description table String File path, relative to the behavior pack's path, to the loot table file
cooldown	Decimal	0.0	Time in seconds before this entity can be interacted with again
hurt_item	Integer	0	The amount of damage the item will take when used to interact with this entity. A value of 0 means the item won't lose durability
interact_text	String		Text to show when the player is able to interact in this way with this entity when playing with Touch-screen controls
on_interact	String		An event identifier to fire when the interaction occurs
particle_on_start	JSON Object		Particle effect that will be triggered at the start of the interaction Name Type Default Value Description particle_offset_towards_interactor Boolean false Whether or not the particle will appear closer to who performed the interaction particle_type String The type of particle that will be spawned particle_y_offset Decimal 0.0 Will offset the particle this amount in the y direction
play_sounds	Array		An array of sound identifiers to play when the interaction occurs
spawn_entities	Array		An array of entity identifiers to spawn when the interaction occurs
spawn_items	JSON Object		Loot table with items to drop on the ground upon successful interaction Name Type Default Value Description table String File path, relative to the behavior pack's path, to the loot table file
swing	Boolean	false	If true, the player will do the 'swing' animation when interacting with this entity
transform_to_item	String		The item used will transform to this item upon successful interaction. Format: itemName:auxValue
use_item	Boolean	false	If true, the interaction will use an item

minecraft:inventory#

Name	Type	Default Value	Description
additional_slots_per_strength	Integer	0	Number of slots that this entity can gain per extra strength
can_be_siphoned_from	Boolean	false	If true, the contents of this inventory can be removed by a hopper
container_type	String	none	Type of container this entity has. Can be horse, minecart_chest, minecart_hopper, inventory, container or hopper
inventory_size	Integer	5	Number of slots the container has
private	Boolean	false	If true, only the entity can access the inventory
restrict_to_owner	Boolean	false	If true, the entity's inventory can only be accessed by its owner or itself

minecraft:inventory_container#

// This example will check the players third inventory item slot for a specific item after the player attacks an entity.
system.listenForEvent("minecraft:player_attacked_entity", function(eventData) {
    // Get the players inventory
    let playerInventory = system.getComponent(eventData.data.player, "minecraft:inventory_container");
    // Get the item at the third slot in the inventory
    let thirdItemSlot = playerInventory.data[2];
    // Destroy the attacked entity if the player has an apple in their third item slot
    if (thirdItemSlot.item == "minecraft:apple") {
        system.destroyEntity(eventData.data.attacked_entity);
    }
});

minecraft:lookat#

Defines the behavior when another entity looks at this entity.

Name	Type	Default Value	Description
allow_invulnerable	Boolean	false	If true, invulnerable entities (e.g. Players in creative mode) are considered valid targets.
filters	Minecraft Filter		Defines the entities that can trigger this component.
look_cooldown	Range [a, b]	[0, 0]	The range for the random amount of time during which the entity is 'cooling down' and won't get angered or look for a target.
look_event	String		The event identifier to run when the entities specified in filters look at this entity.
search_radius	Decimal	10	Maximum distance this entity will look for another entity looking at it.
set_target	Boolean	true	If true, this entity will set the attack target as the entity that looked at it.

minecraft:nameable#

Name	Type	Default Value	Description
allow_name_tag_renaming	Boolean	true	If true, this entity can be renamed with name tags
always_show	Boolean	false	If true, the name will always be shown
default_trigger	String		Trigger to run when the entity gets named
name	String		The current name of the entity, empty if the entity hasn't been named yet, making this non-empty will apply the name to the entity
name_actions	JSON Object		Describes the special names for this entity and the events to call when the entity acquires those names Name Type Default Value Description name_filter List List of special names that will cause the events defined in 'on_named' to fire on_named String Event to be called when this entity acquires the name specified in 'name_filter'

minecraft:position#

Name	Type	Default Value	Description
x	Decimal	0.0	Position along the X-Axis (east-west) of the entity
y	Decimal	0.0	Position along the Y-Axis (height) of the entity
z	Decimal	0.0	Position along the Z-Axis (north-south) of the entity

minecraft:rotation#

Name	Type	Default Value	Description
x	Decimal	0.0	Controls the head rotation looking up and down
y	Decimal	0.0	Controls the body rotation parallel to the floor

minecraft:shooter#

Name	Type	Default Value	Description
auxVal	Integer	-1	ID of the Potion effect to be applied on hit
def	String		Entity identifier to use as projectile for the ranged attack. The entity must have the projectile component to be able to be shot as a projectile

minecraft:spawn_entity#

Adds a timer after which this entity will spawn another entity or item (similar to vanilla's chicken's egg-laying behavior).

Name	Type	Default Value	Description
filters	Minecraft Filter		If present, the specified entity will only spawn if the filter evaluates to true.
max_wait_time	Integer	600	Maximum amount of time to randomly wait in seconds before another entity is spawned.
min_wait_time	Integer	300	Minimum amount of time to randomly wait in seconds before another entity is spawned.
num_to_spawn	Integer	1	The number of entities of this type to spawn each time that this triggers.
should_leash	Boolean	false	If true, this the spawned entity will be leashed to the parent.
single_use	Boolean	false	If true, this component will only ever spawn the specified entity once.
spawn_entity	String		Identifier of the entity to spawn, leave empty to spawn the item defined above instead.
spawn_event	String	minecraft:entity_born	Event to call when the entity is spawned.
spawn_item	String	egg	Item identifier of the item to spawn.
spawn_method	String	born	Method to use to spawn the entity.
spawn_sound	String	plop	Identifier of the sound effect to play when the entity is spawned.

minecraft:tag#

minecraft:teleport#

Name	Type	Default Value	Description
dark_teleport_chance	Decimal	0.01	Modifies the chance that the entity will teleport if the entity is in darkness
light_teleport_chance	Decimal	0.01	Modifies the chance that the entity will teleport if the entity is in daylight
max_random_teleport_time	Decimal	20	Maximum amount of time in seconds between random teleports
min_random_teleport_time	Decimal	0	Minimum amount of time in seconds between random teleports
random_teleport_cube	Vector [a, b, c]	[32, 16, 32]	Entity will teleport to a random position within the area defined by this cube
random_teleports	Boolean	true	If true, the entity will teleport randomly
target_distance	Decimal	16	Maximum distance the entity will teleport when chasing a target
target_teleport_chance	Decimal	1	The chance that the entity will teleport between 0.0 and 1.0. 1.0 means 100%

minecraft:ticking_area_description#

Name	Type	Default Value	Description
is_circle	Boolean		Is the area a circle. If false the area is a square.
max	Vector [a, b, c]		(if area is a square) The edge of the area.
name	String		The name of the area.
origin	Vector [a, b, c]		The origin position of the area.
radius	Vector [a, b, c]		(if area is a circle) The radius of the area.

minecraft:tick_world#

Name	Type	Description
distance_to_players	Decimal	distance_to_players
never_despawn	Boolean	Whether or not this ticking area will despawn when a player is out of range
radius	Integer	The radius in chunks of the ticking area
ticking_area	Entity Ticking Area JS API Object	The ticking area entity that is attached to this entity

minecraft:transformation#

Name	Type	Default Value	Description
add	JSON Object		List of components to add to the entity after the transformation Name Type Default Value Description component_groups List Names of component groups to add
begin_transform_sound	String		Sound to play when the transformation starts
delay	JSON Object		Defines the properties of the delay for the transformation Name Type Default Value Description block_assist_chance Decimal 0.0 Chance that the entity will look for nearby blocks that can speed up the transformation. Value must be between 0.0 and 1.0 block_chance Decimal 0.0 Chance that, once a block is found, will help speed up the transformation block_max Integer 0 Maximum number of blocks the entity will look for to aid in the transformation. If not defined or set to 0, it will be set to the block radius block_radius Integer 0 Distance in Blocks that the entity will search for blocks that can help the transformation block_types List List of blocks that can help the transformation of this entity keep_owner Boolean If this entity is owned by another entity, it should remain owned after transformation value Decimal 0.0 Time in seconds before the entity transforms
drop_equipment	Boolean		Cause the entity to drop all equipment upon transformation
into	String		Entity Definition that this entity will transform into
transformation_sound	String		Sound to play when the entity is done transforming

Client Components#

minecraft:molang#

Code Example:

let molangComponent = this.createComponent(entity, "minecraft:molang"); 
molangComponent["variable.molangexample"] = 1.0; 
this.applyComponentChanges(molangComponent); 

Block Components#

minecraft:blockstate#

Code Example:

let blockstateComponent = this.getComponent(block, "minecraft:blockstate");
blockstateComponent.data.coral_color = "blue";
this.applyComponentChanges(block, blockstateComponent);

Script Events#

Here you can find the list of events that you can listen for and respond to in your scripts.

Client Events#

Listening Events#

minecraft:client_entered_world#

minecraft:hit_result_changed#

Name	Type	Description
entity	Entity JS API Object	The entity that was hit or null if it fired when moving off of an entity
position	Vector [a, b, c]	The position of the entity that was hit or null if it fired when moving off an entity

Code Example:

Responding to hit_result_changed

const mySystem = client.registerSystem(0, 0);

mySystem.initialize = function() {
  this.listenForEvent("minecraft:hit_result_changed", (eventData) => this.onHitChanged(eventData));
};

mySystem.onHitChanged = function(eventData) {
  if(eventData.position != null) {
    let chatEvent = this.createEventData("minecraft:display_chat_event");
    chatEvent.data.message = "Hit at x:" + eventData.position.x + " y:" + eventData.position.y + " z:" + eventData.position.z;
    this.broadcastEvent("minecraft:display_chat_event", chatEvent);
  }
};

minecraft:hit_result_continuous#

Name	Type	Description
entity	Entity JS API Object	The entity that was hit or null if it not pointing at an entity
position	Vector [a, b, c]	The position of the entity that was hit or block that was hit

Code Example:

Responding to hit_result_continuous

const mySystem = client.registerSystem(0, 0);

mySystem.initialize = function() {
  this.listenForEvent("minecraft:hit_result_continuous", (eventData) => this.onHit(eventData));
};

mySystem.onHit = function(eventData) {
  if(eventData.position != null) {
    let chatEvent = this.createEventData("minecraft:display_chat_event");
    chatEvent.data.message = "Position at x:" + eventData.position.x + " y:" + eventData.position.y + " z:" + eventData.position.z;
    this.broadcastEvent("minecraft:display_chat_event", chatEvent);
  }
};

minecraft:pick_hit_result_changed#

Name	Type	Description
entity	Entity JS API Object	The entity that was hit or null if it fired when moving off of an entity
position	Vector [a, b, c]	The position of the entity that was hit or null if it fired when moving off an entity

Code Example:

Responding to pick_hit_result_changed

const mySystem = client.registerSystem(0, 0);

mySystem.initialize = function() {
  this.listenForEvent("minecraft:pick_hit_result_changed", (eventData) => this.onPickChanged(eventData));
};

mySystem.onPickChanged = function(eventData) {
  if(eventData.position != null) {
    let chatEvent = this.createEventData("minecraft:display_chat_event");
    chatEvent.data.message = "Pick at x:" + eventData.position.x + " y:" + eventData.position.y + " z:" + eventData.position.z;
    this.broadcastEvent("minecraft:display_chat_event", chatEvent);
  }
};

minecraft:pick_hit_result_continuous#

Name	Type	Description
entity	Entity JS API Object	The entity that was hit or null if it not pointing at an entity
position	Vector [a, b, c]	The position of the entity that was hit or block that was hit

Code Example:

Responding to pick_hit_result_continuous

const mySystem = client.registerSystem(0, 0);

mySystem.initialize = function() {
  this.listenForEvent("minecraft:pick_hit_result_continuous", (eventData) => this.onPick(eventData));
};

mySystem.onPick = function(eventData) {
  if(eventData.position != null) {
    let chatEvent = this.createEventData("minecraft:display_chat_event");
    chatEvent.data.message = "Pick at:" + eventData.position.x + " y:" + eventData.position.y + " z:" + eventData.position.y + " z:" + eventData.position.z;
    this.broadcastEvent("minecraft:display_chat_event", chatEvent);
  }
};

Trigger-able Events#

minecraft:display_chat_event#

Name	Type	Default Value	Description
message	String		The chat message that will be displayed

Code Example:

Trigger chat event

const mySystem = server.registerSystem(0, 0);

mySystem.update = function() {
  let chatEvent = this.createEventData("minecraft:display_chat_event");
  chatEvent.data.message = "Hello, World!";
  this.broadcastEvent("minecraft:display_chat_event", chatEvent);
};

minecraft:load_ui#

Event Data Parameters

Name	Type	Default Value	Description
options	JSON Object		You can define the following options for the screen by setting their value to true or false: absorbs_input# If true, input will not be passed down to any other screens underneath always_accepts_input# If true, the screen will always accept and process input for as long as it is in the stack, even if other custom UI screens appear on top of it force_render_below# If true, this screen will be rendered even if another screen is on top of it and will render over them, including the HUD is_showing_menu# If true, the screen will be treated as the pause menu and the pause menu won't be allowed to show on top of this screen render_game_behind# If true, the game will continue to be rendered underneath this screen render_only_when_topmost# If true, this screen will only be rendered if it is the screen at the top of the stack should_steal_mouse# If true, the screen will capture the mouse pointer and limit its movement to the UI screen
path	String		The file path to the screen's HTML file

minecraft:send_ui_event#

Custom UI is based on HTML 5. Review the scripting demo for an example of a custom UI file.

Name	Type	Description
data	String	The data for the UI event being triggered
eventIdentifier	String	The identifier of the UI event

minecraft:spawn_particle_attached_entity#

Name	Type	Default Value	Description
effect	String		The identifier of the particle effect you want to attach to the entity. This is the same name you gave the effect in its JSON file
entity	Entity JS API Object		The entity object you want to attach the effect to
offset	Vector [a, b, c]	[0, 0, 0]	The offset from the entity's "center" where you want to spawn the effect

minecraft:spawn_particle_in_world#

Name	Type	Default Value	Description
effect	String		The identifier of the particle effect you want to attach to spawn. This is the same name you gave the effect in its JSON file
position	Vector [a, b, c]	[0, 0, 0]	The position in the world where you want to spawn the effect

minecraft:unload_ui#

minecraft:script_logger_config#

Name	Type	Default Value	Description
log_errors	Boolean	false	Set to true to log any scripting errors that occur on the client
log_information	Boolean	false	Set to true to log any general scripting information that occurs on the client. This includes any logging done with client.log()
log_warnings	Boolean	false	Set to true to log any scripting warnings that occur on the client

Server Events#

Listening Events#

minecraft:entity_attack#

Name	Type	Description
entity	Entity JS API Object	The entity that attacked
target	Entity JS API Object	The entity that was targeted in the attack

minecraft:player_attacked_entity#

Name	Type	Description
attacked_entity	Entity JS API Object	The entity that was attacked by the player
player	Entity JS API Object	The player that attacked an entity

minecraft:entity_acquired_item#

Name	Type	Description
acquired_amount	Integer	The total number of items acquired by the entity during this event
acquisition_method	String	The way the entity acquired the item
entity	Entity JS API Object	The entity who acquired the item
item_stack	ItemStack JS API Object	The item that was acquired
secondary_entity	Entity JS API Object	If it exists, the entity that affected the item before it was acquired. Example: A player completes a trade with a villager. The `entity` property would be the player and the `secondary_entity` would be the villager

minecraft:entity_carried_item_changed#

Name	Type	Description
carried_item	ItemStack JS API Object	The item that is now in the entities hands
entity	Entity JS API Object	The entity that changed what they were carrying
hand	String	Defines which hand the item was equipped to. Either main or offhand.
previous_carried_item	ItemStack JS API Object	The item that was previously in the entities hands

minecraft:entity_created#

Name	Type	Description
entity	Entity JS API Object	The entity that was just created

minecraft:entity_definition_event#

Name	Type	Description
entity	Entity JS API Object	The entity that was affected
event	String	The event that was triggered

minecraft:entity_death#

Name	Type	Description
block_position	JavaScript Object	The position of the block that killed the entity
cause	String	The cause of the entity's death
entity	Entity JS API Object	The entity that died
killer	Entity JS API Object	The entity that killed the entity
projectile_type	String	The type of the projectile that killed the entity

minecraft:entity_dropped_item#

Name	Type	Description
entity	Entity JS API Object	The entity who dropped the item
item_stack	ItemStack JS API Object	The item that was dropped

minecraft:entity_equipped_armor#

Name	Type	Description
entity	Entity JS API Object	The entity who is equipping the armor
item_stack	ItemStack JS API Object	The armor that is being equipped
slot	String	Defines which slot the item was equipped to.

minecraft:entity_hurt#

Name	Type	Description
absorbed_damage	Integer	The amount the damage was reduced by by the entity's absorption effect
attacker	Entity JS API Object	Present only when damaged by an entity or projectile. The entity that attacked and caused the damage
block_position	Vector [a, b, c]	Present only when damaged by a block. This is the position of the block that hit the entity
cause	String	The way the entity took damage. Refer to the Damage Source documentation for a complete list of sources
damage	Integer	The amount of damage the entity took after immunity and armor are taken into account
entity	Entity JS API Object	The entity that took damage
projectile_type	String	Present only when damaged by a projectile. This is the identifier of the projectile that hit the entity

minecraft:entity_move#

Name	Type	Description
entity	Entity JS API Object	The entity that moved

minecraft:entity_sneak#

Name	Type	Description
entity	Entity JS API Object	The entity that changed their sneaking state
sneaking	Boolean	If true, the entity just started sneaking. If false, the entity just stopped sneaking

minecraft:entity_start_riding#

Name	Type	Description
entity	Entity JS API Object	The rider
ride	Entity JS API Object	The entity being ridden

minecraft:entity_stop_riding#

Name	Type	Description
entity	Entity JS API Object	The entity that was riding another entity
entity_is_being_destroyed	Boolean	If true, the rider stopped riding because they are now dead
exit_from_rider	Boolean	If true, the rider stopped riding by their own decision
switching_rides	Boolean	If true, the rider stopped riding because they are now riding a different entity

minecraft:entity_tick#

Name	Type	Description
entity	Entity JS API Object	The entity that was ticked

minecraft:entity_use_item#

Name	Type	Description
entity	Entity JS API Object	The entity who is using the item
item_stack	ItemStack JS API Object	The item that is being used
use_method	String	The way the entity used the item

minecraft:block_destruction_started#

Name	Type	Description
block_position	JavaScript Object	The position of the block that is being destroyed
player	Entity JS API Object	The player that started destoying the block

minecraft:block_destruction_stopped#

Name	Type	Description
block_position	JavaScript Object	The position of the block that was being destroyed
destruction_progress	Decimal	How far along the destruction was before it was stopped (0 - 1 range)
player	Entity JS API Object	The player that stopped destoying the block

minecraft:block_exploded#

Name	Type	Description
block_identifier	String	The identifier of the block that was destroyed
block_position	JavaScript Object	The position of the block that was destroyed by the explosion
cause	String	The cause of the block's destruction
entity	Entity JS API Object	The entity that exploded

minecraft:block_interacted_with#

Name	Type	Description
block_position	JavaScript Object	The position of the block that is being interacted with
player	Entity JS API Object	The player that interacted with the block

minecraft:piston_moved_block#

Name	Type	Description
block_position	JavaScript Object	The position of the block that was moved
piston_action	String	The action the piston took, "extended" or "retracted"
piston_position	JavaScript Object	The position of the piston that moved the block

minecraft:player_destroyed_block#

Name	Type	Description
block_identifier	String	The identifier of the block that was destroyed
block_position	JavaScript Object	The position of the block that was destroyed
player	Entity JS API Object	The player that destroyed the block

minecraft:player_placed_block#

Name	Type	Description
block_position	JavaScript Object	The position of the block that was placed
player	Entity JS API Object	The player that placed the block

minecraft:play_sound#

Name	Type	Default Value	Description
pitch	Decimal	1.0	The pitch of the sound effect. A value of 1.0 will play the sound effect with regular pitch
position	Vector [a, b, c]	[0, 0, 0]	The position in the world we want to play the sound at
sound	String		The identifier of the sound you want to play. Only sounds defined in the applied resource packs can be played
volume	Decimal	1.0	The volume of the sound effect. A value of 1.0 will play the sound effect at the volume it was recorded at

minecraft:projectile_hit#

Name	Type	Description
entity	Entity JS API Object	The entity that was hit by the projectile, if any
owner	Entity JS API Object	The entity that fired the projectile
position	Vector [a, b, c]	The position of the collision
projectile	Entity JS API Object	The projectile in question

minecraft:weather_changed#

Name	Type	Description
dimension	String	The name of the dimension where the weather change happened
lightning	Boolean	Tells if the new weather has lightning
raining	Boolean	Tells if the new weather has rain

Trigger-able Events#

minecraft:entity_definition_event#

Name	Type	Default Value	Description
entity	Entity JS API Object		The entity object you want to attach the effect to
event	String		The identifier of the event to trigger on that entity. Both built-in (minecraft:) and custom events are supported

minecraft:display_chat_event#

Name	Type	Default Value	Description
message	String		The chat message that will be displayed

minecraft:execute_command#

Name	Type	Default Value	Description
command	String		The command that will be run

minecraft:play_sound#

Name	Type	Default Value	Description
pitch	Decimal	1.0	The pitch of the sound effect. A value of 1.0 will play the sound effect with regular pitch
position	Vector [a, b, c]	[0, 0, 0]	The position in the world we want to play the sound at
sound	String		The identifier of the sound you want to play. Only sounds defined in the applied resource packs can be played
volume	Decimal	1.0	The volume of the sound effect. A value of 1.0 will play the sound effect at the volume it was recorded at

minecraft:spawn_particle_attached_entity#

Name	Type	Default Value	Description
effect	String		The identifier of the particle effect you want to attach to the entity. This is the same identifier you gave the effect in its JSON file
entity	Entity JS API Object		The entity object you want to attach the effect to
offset	Vector [a, b, c]	[0, 0, 0]	The offset from the entity's "center" where you want to spawn the effect

minecraft:spawn_particle_in_world#

Name	Type	Default Value	Description
dimension	String	overworld	The dimension in which you want to spawn the effect. Can be "overworld", "nether", or "the end"
effect	String		The identifier of the particle effect you want to attach to spawn. This is the same name you gave the effect in its JSON file
position	Vector [a, b, c]	[0, 0, 0]	The position in the world where you want to spawn the effect

minecraft:script_logger_config#

Name	Type	Default Value	Description
log_errors	Boolean	false	Set to true to log any scripting errors that occur on the server
log_information	Boolean	false	Set to true to log any general scripting information that occurs on the server. This includes any logging done with server.log()
log_warnings	Boolean	false	Set to true to log any scripting warnings that occur on the server

Scripting System#

The Minecraft Script Engine uses the JavaScript language.
You can write JavaScript scripts and bundle them with Behavior Packs to listen and respond to game events, get and modify data in components that entities have, and affect different parts of the game.

Demos#

Demo	Last Updated	Download Link
Mob Arena	10/24/2018	https://aka.ms/minecraftscripting_mobarena
Turn-Based RPG	10/24/2018	https://aka.ms/minecraftscripting_turnbased

Known Issues#

Issue	Workaround
Scripts are not loaded properly from archived packs
Custom UI doesn't work in VR or MR mode
Custom UI doesn't retain state upon suspend and resume
Exiting a world without scripts and entering one that has scripts might cause the wrong world to load
Calling removeEntity on a dying entity might cause the game to crash

Breaking Changes#

Category	Change
UI
Components
Events
Events
Events
Events

Pre-Requisites#

NOTE: Scripts are only supported on Windows 10 PCs at the moment. If you try to open a world with scripts on a device that doesn't support scripts, you will see an error message letting you know you can't enter the world.

Software	Minimum	Recommended
Code Editor	Visual Studio Code or any plain-text editor	Visual Studio Community 2017 with the following components installed: 'JavaScript diagnostics', 'JavaScript and TypeScript language support', 'Just-In-Time debugger'
Debugger	N/A	Visual Studio Community 2017
Minecraft	Minecraft on your Windows 10 device	Minecraft on your Windows 10 device
Other	Vanilla Behavior Pack available from https://aka.ms/behaviorpacktemplate	Vanilla Behavior Pack available from https://aka.ms/behaviorpacktemplate
Storage	1.0 GB of free space for text editor, game, and scripts	3.0 GB of free space for Visual Studio, game, and scripts

Getting Started#

Once you have downloaded the Behavior Pack, unzip it to a folder. Inside the Behavior Pack you will find the scripts folder which contains all the scripting files you want to run.
In the scripts folder you will find two folders: one for client scripts and one for server scripts.
-Server Scripts: These scripts run on the server side of the game. This includes spawning new entities, adding components, or modifying components on an entity.
-Client Scripts: These scripts run on each individual player's side of the game. This is a good place to respond to events and manage anything specific to the player.
Once you have chosen whether you are making a client or server script, simply add a new blank text file with .js extension to the appropriate folder, and open it in your preferred code editor. Then code away! You can have as many or as few JavaScript files as you want here (the name of the files doesn't matter) and they will all be run independently of each other!

NOTE: For scripts to be run by the game, you need to enable Experimental Gameplay on the world where you will run scripts on. This will be necessary while scripting is still in beta.
When entering a world that has client scripts in it, you will be prompted to accept that you wish to run scripts on your device (this will show up both for local worlds as well as multiplayer worlds).
Additionally, if your pack contains client scripts, you need to include a client_data module in the pack's manifest. This tells the game anything in the scripts/client folder needs to be sent over to the clients. Please refer to the Add-on Documentation page for more information on the pack's manifest contents.

Folder Structure

Example of manifest module needed for client scripts

        {
            "description": "Example client scripts module",
            "type": "client_data",
            "uuid": "c05a992e-482a-455f-898c-58bbb4975e47",
            "version": [0, 0, 1]
        }

vanilla_behavior_pack

|-scripts
|--client
|---myClientScript.js
|--server
|---myServerScript.js
|-manifest.json
|-pack_icon.png

Structure of a Script#

These are, in a way, the required parts of a script but they are by no means the only parts you can have. You can create additional methods as needed - just make sure they are called from somewhere in one of the methods below!

1. System Registration#

Name	Type	Description
majorVersion	Integer	This is the major version of the Minecraft Script Engine your script was designed to work with
minorVersion	Integer	This is the revision of the Minecraft Script Engine your script was designed to work with

Code Examples:

Client System

let sampleClientSystem = client.registerSystem(0, 0);

Server System

let sampleServerSystem = server.registerSystem(0, 0);

2. System Initialization#

You can use this to set up the environment for your script: register custom components and events, sign up event listeners, etc. This will run BEFORE the world is ready and the player has been added to it. This function should be used to initialize variables and setup event listeners. You shouldn't try to spawn or interact with any entities at this point! You should also avoid interaction with UI elements or sending messages to the chat window since this is called before the player is ready.

Code Example:

sampleSystem.initialize = function() {
  //register event data, register components, register queries, listen for events
};

3. System Update#

Code Example:

sampleSystem.update = function() {
  //Update all the things
};

4. System Shutdown#

Code Example:

sampleSystem.shutdown = function() {
  //Cleanup script only things
};

Debugging#

There are two ways to tell what happened when something goes wrong with a script: in-game and advanced, which we will describe below. You only need the game and your script to debug in-game, but you will need a Windows 10 PC and Visual Studio installed for the advanced debugging.

In-Game#

We strongly encourage you to build further debug messages and tools into your scripts while working on them. This will help you discern when something isn't working quite right. Reach out on the official Discord channel if you need additional help: https://discord.gg/Minecraft

Real-Time (Advanced)#

If you installed Visual Studio with the components mentioned in the "Recommended" section of this document you will have installed and enabled the Just-In-Time Debugger. This tool will pop-up a message from Visual Studio whenever an exception occurs in your script and allow you to open Visual Studio on the line of your script that broke.

Additionally, you can connect to the Script Engine manually and debug your code. You can use remote debugging to connect and debug Minecraft running on another device. Please refer to the Visual Studio Debugger documentation above for instructions on how to use remote debugging.
First you need to start up Visual Studio. If this is the first time you have launched Visual Studio after installation, we suggest setting up your environment for JavaScript development and logging in to your Microsoft account when prompted. This will set up the Visual Studio interface with the most important tools you will need.
Once you have Visual Studio open you should launch Minecraft. Then create a new world with Experimental Gameplay enabled and apply the Behavior Pack containing your scripts.
After creating the world go back to Visual Studio and click on the Debug menu. Then click on "Attach to Process". In the window that opens there will be a search box titled Filter Process. Click on it and type Minecraft.
Once the list is narrowed down to only the instance of Minecraft running, you can verify that the Script Engine is running by looking at the Type column. This will say Script and either x86 or x64.

Select the process and click on Attach to attach the debugger to the game. Now you will be able to press the Pause button to pause the Script Engine when the next line of script code runs. This allows you to inspect the values of variables in your script and break into Visual Studio if an error occurs in your code.
WARNING: When you hit a breakpoint to step through code with a debugger, it is possible for a client to time out and disconnect or for the server to disconnect all players.

User-Defined Components#

User-Defined components are a special kind of component that can be defined in script and no built-in game system acts on it.
The component needs to be registered with the Script Engine by giving it a name and a set of fields in the format name:value. Once applied, the component behaves like any of the built-in components: you can get it from an entity, modify its values, and apply the changes.
Currently User-Defined components are the only components that can be dynamically added and removed from an entity using scripts. They don't need to be previously defined in an entity's JSON file. In the current version these components will NOT be saved out or loaded back in: they only exist while the entity is there and need to be added back when reloading the level.

Code Example:

Component Registration

this.registerComponent("myNamespace:myComponent", { myString: "TamerJeison", myInt: 42, myFloat: 1.0, myArray: [1, 2, 3] });