SCRIPTING DOCUMENTATION
Version: 1.9.0.10

Index

Scripting System
Demos
Known Issues
Pre-Requisites
Getting Started
Structure of a Script
Debugging
Script Bindings
Entity Bindings
Component Bindings
Event Bindings
Entity Queries
Script Components
Client Components
Server Components
User-Defined Components
Script Events
Client Events
Server Events
Back to top

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

Here are some demos from your friends at Minecraft to help you get started with scripting. Simply unzip them to check out the code, or import them as a .mcpack to play with them

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
Back to top

Known Issues

This is the list of currently known issues with the Minecraft Script Engine

Issue Workaround
Custom UI doesn't retain state upon suspend and resume Currently there's no workaround for this issue
Custom UI doesn't work in VR or MR mode Currently you will only be able to use custom UI when running the game in regular mode
Custom UI draws on top of the chat screen and chat pop-ups If you are using custom UI we recommend using Visual Studio to debug your scripts. Script errors are printed out to the chat but they won't be visible if you have a custom UI due to this bug
Custom UI prevents menus (such as the pause menu) from displaying You need to close and re-open Minecraft to exit out of a world that uses custom UI
Custom UI resets after the application is suspended Currently there's no workaround for this issue
Exiting a world without scripts and entering one that has scripts might cause the wrong world to load Restart Minecraft before loading a new world with scripts
Scripts are not loaded properly from archived packs Unzip script packs before applying them to a world. If you import a script pack with the .mcpack extension, it will unzip it for you
Pressing the Leave button at the end of the demo will display some errors The errors are from running the /fill command to replace a block with a block that's already there and can be safely ignored
There might be an extra Ocelot at the beginning of the game This is due to the built-in behavior of Ocelot to spawn with a litter but is otherwise a harmless issue
Back to top

Pre-Requisites

So you want to make your own Scripts? That's awesome! In this section you will find the list of minimum and recommended software you will need.
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
Back to top

Getting Started

First you will need to download the latest Vanilla Behavior Pack. You can get this from the following link: https://aka.ms/behaviorpacktemplate
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).

Folder Structure

vanilla_behavior_pack

Back to top

Structure of a Script

In this section you can find a quick description of the basic structure of a JavaScript script file for the Minecraft Script Engine. If you would like to learn more about JavaScript or want to follow a fundamentals tutorial, you can check the official documentation on the Mozilla Developer Network here: https://developer.mozilla.org/docs/Web/JavaScript
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

First off we need to register the system for our file. This signs up our script to be set-up either on the client or server threads of the game. Generally speaking, you will choose based on whether you put the script file in the client or server folders. To do that simply call registerSystem on either the client or server and give it the version of the API you require.

Parameters

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

Server System

Back to top

2. System Initialization

This is the first method that gets called immediately after the system is registered. It will run as soon as the script loads at world start.
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, so you shouldn't try to spawn any entities here!

Code Example:



Back to top

3. System Update

This method gets called once every game tick. The server and client tick at 20 times per second. This is a good place to get, check, and react to component changes.

Code Example:



Back to top

4. System Shutdown

This method gets called when the Minecraft Script Engine is shutting down. For the client this is when they leave the world; for the server this is after the last player has exited the world.

Code Example:



Back to top



Debugging

Your script isn't working or doing what you want it to do? Fret not! We have built some debugging capabilities into the Script Engine to help you figure out what's going on with your script. If you are new to programming or want to learn more about debugging we suggest checking out the documentation about debugging with Visual Studio available here: https://docs.microsoft.com/visualstudio/debugger

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

When you run a script in the game, the Script Engine will print out error messages whenever something goes wrong. For example, if you try to get a component that the script engine doesn't know about you will get an error.
To look at these messages you can open the chat screen which will have all the generated error messages there; or you can open the log file that the game generated. The location of the log file varies by platform. On Windows 10 you can find the log file in ' %APPDATA%\..\Local\Packages\Microsoft.MinecraftUWP_8wekyb3d8bbwe\LocalState\logs '
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
Back to top

Real-Time (Advanced)

If you have a Windows 10 PC with Visual Studio installed, you can attach the Visual Studio debugger and debug your script in real-time.
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.
Back to top





Script Bindings

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

Entity Bindings

createEntity()

Creates an empty entity with no components and does not place it in the world.

Return Value

Type Value Description
JavaScript Object object An EntityObject representing the newly created entity
Name Type 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 we are using. Can be: entity, item_entity, level, component, query
id Integer READ ONLY. This is the unique identifier of the entity in the world
JavaScript Object null Something went wrong when creating the entity
Back to top



createEntity(Type, TemplateIdentifier)

Creates an entity and applies the specified template as defined in JSON. This allows you to quickly create an entity from the applied Behavior Packs as the base for an entity created in scripting. The entity will be spawned into the world with all the components, component groups, and event triggers that are defined in the JSON file of the identifier specified. Only works on scripts registered on the server.

Parameters

Name Type Description
Type String Specifies the type of the entity that is being created by the template. Valid inputs are `entity` and `item_entity`
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
Back to top

Return Value

Type Value Description
JavaScript Object object An EntityObject representing the newly created entity
Name Type 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 we are using. Can be: entity, item_entity, level, component, query
id Integer READ ONLY. This is the unique identifier of the entity in the world
JavaScript Object null Something went wrong when creating the entity
Back to top



destroyEntity(EntityObject)

Destroys an entity identified by the EntityObject. If the entity exists in the world this will remove it from the world and destroy it. This also makes the EntityObject no longer valid - you should only destroy an entity after you are done with it and no longer need to reference it again. This does NOT kill the entity. There won't be an event for its death: it will be removed.

Parameters

Name Type Description
EntityObject JavaScript Object The EntityObject that was retrieved from a call to createEntity() or retrieved from an event
Back to top

Return Value

Type Value Description
Boolean true The entity was successfully destroyed
JavaScript Object null Something went wrong when destroying the entity
Back to top



isValidEntity(EntityObject)

Checks if the given EntityObject corresponds to a valid entity.

Parameters

Name Type Description
EntityObject JavaScript Object The EntityObject that was retrieved from a call to createEntity() or retrieved from an event
Back to top

Return Value

Type Value Description
Boolean true The entity is in the Script Engine's database of entities
Boolean false The entity is not in the Script Engine's database of entities
JavaScript Object null Something went wrong when validating the entity
Back to top





Component Bindings

registerComponent(ComponentIdentifier, ComponentData)

Creates a custom component that only exists in script. It can be then added, removed, and updated from entities. These custom components only exist while the Script Engine is running.

Parameters

Name Type Description
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'
ComponentData JavaScript Object A JavaScript Object that defines the name of the fields and the data each field holds inside the component.
Back to top

Return Value

Type Value Description
Boolean true The component was successfully registered
JavaScript Object null Something went wrong when registering the component
Back to top



createComponent(EntityObject, ComponentIdentifier)

Creates the specified component and adds it to the entity. This should only be used with custom components which need to be registered first. If the entity already has the component, this will retrieve the component already there instead.

Parameters

Name Type Description
EntityObject JavaScript Object The EntityObject that was retrieved from a call to createEntity() or retrieved from an event
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()
Back to top

Return Value

Type Value Description
JavaScript Object object An object with the following fields, and additionally, all the fields as defined in the component
Name Type 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 we are using. Can be: entity, item_entity, level, component, query
JavaScript Object null Something went wrong when creating the component
Back to top



hasComponent(EntityObject, ComponentIdentifier)

Checks if the given entity has the specified component.

Parameters

Name Type Description
EntityObject JavaScript Object The EntityObject that was retrieved from a call to createEntity() or retrieved from an event
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()
Back to top

Return Value

Type Value Description
Boolean true The EntityObject has the component
Boolean false The EntityObject doesn't have the component
JavaScript Object null An unknown component was passed in or something else went wrong when checking if the EntityObject had the component
Back to top



getComponent(EntityObject, ComponentIdentifier)

Looks for the specified component in the entity. If it exists, retrieves the data from the component and returns it.

Parameters

Name Type Description
EntityObject JavaScript Object The EntityObject that was retrieved from a call to createEntity() or retrieved from an event
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()
Back to top

Return Value

Type Value Description
JavaScript Object object An object with the following fields, and additionally, all the fields as defined in the component
Name Type 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 we are using. Can be: entity, item_entity, level, component, query
JavaScript Object null The entity did not have the component or something went wrong when getting the component
Back to top



applyComponentChanges(entityObject, componentObject)

Applies the component and any changes made to it in script back to the entity. What this means for each component can be slightly different: it makes the component reload on the entity with the new data as if it had just been added to the entity.

Parameters

Name Type Description
entityObject JavaScript Object The entity object that we are applying the component changes to
componentObject JavaScript Object The component object retrieved from the entity that was returned by either createComponent() or getComponent()
Back to top

Return Value

Type Value Description
Boolean true The component was successfully updated
JavaScript Object null Something went wrong when updating the component
Back to top



destroyComponent(EntityObject, ComponentIdentifier)

Removes the specified component from the given entity. If the entity has the component, it will be removed. Currently this only works with custom components and can't be used to remove components defined for an entity in JSON.

Parameters

Name Type Description
EntityObject JavaScript Object The EntityObject that was retrieved from a call to createEntity() or retrieved from an event
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()
Back to top

Return Value

Type Value Description
Boolean true The component was successfully removed from the entity
JavaScript Object null The entity did not have the component or something went wrong when removing the component
Back to top





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.

broadcastEvent(EventIdentifier, EventData)

Allows you to trigger an event with the desired data from script. Anything that signed up to listen for the event will be notified and the given data delivered to them.

Parameters

Name Type Description
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
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
Back to top

Return Value

Type Value Description
Boolean true Successfully broadcasted the event
JavaScript Object null Something went wrong when broadcasting the event
Back to top



listenForEvent(EventIdentifier, CallbackObject)

Allows you to register a JavaScript object that gets called whenever the specified event is broadcast. The event can either be a built-in event or an event specified in script.

Parameters

Name Type Description
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
CallbackObject JavaScript Object The JavaScript object that will get called whenever the event is broadcast
Back to top

Return Value

Type Value Description
Boolean true Successfully registered to listen for the event
JavaScript Object null Something went wrong when registering the event for listening
Back to top





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 Description
JavaScript Object object An object containing the ID of the query
Name Type 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 we are using. Can be: entity, item_entity, level, component, query
id Integer READ ONLY. This is the unique identifier of the query
JavaScript Object null Something went wrong when creating the query
Back to top



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.

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. If the component you used doesn't have the field you defined here, the field will be ignored
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. If the component you used doesn't have the field you defined here, the field will be ignored
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. If the component you used doesn't have the field you defined here, the field will be ignored
Back to top

Return Value

Type Value Description
JavaScript Object object An object containing the ID of the query
Name Type 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 we are using. Can be: entity, item_entity, level, component, query
id Integer READ ONLY. This is the unique identifier of the query
JavaScript Object null Something went wrong when creating the query
Back to top



addFilterToQuery(Query, ComponentIdentifier)

By default no filters are added. This will allow queries to capture all entities.

Parameters

Name Type Description
Query JavaScript Object The object containing the ID of the query that you want to apply the filter to
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
Back to top

getEntitiesFromQuery(Query)

Allows you to fetch the entities captured by a query.

Parameters

Name Type Description
Query JavaScript Object This is the query you registered earlier using registerQuery()
Back to top

Return Value

Type Value Description
Array array An array of EntityObjects representing the entities found within the query
JavaScript Object null Something went wrong when creating the entity
Back to top



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
Query JavaScript Object This is the query you created earlier using registerQuery(...)
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_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_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
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
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
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
Back to top

Return Value

Type Value Description
Array array An array of EntityObjects representing the entities found within the query
JavaScript Object null Something went wrong when creating the entity
Back to top







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.

Client Components

These components only run on the client where the script ran and can only be used from client scripts.

minecraft:molang

The MoLang component gives access to the MoLang variables in an entity. To learn more about MoLang varibles review the add-on documentation. In scripts, you can get and set these varibles that are defined in the entity's JSON files. Because of how the MoLang variables are formatted (variable.isgrazing for example) you must use the [] operator on the object to access the variable. The example below shows how to use the [] operator to access the variable.

Code Example:



Back to top



Server Components

These are the components that run on the server and are synced with all the clients (players) in the world.
As much as possible, the API of each component matches its JSON counterpart (with some differences noted).

minecraft:attack

This component controls the Attack Damage attribute from the entity. It allows you to change the current minimum and maximum values. Once the changes are applied, the current attack of the entity will be reset to the minimum specified. With the minimum and maximum changed to the values specified. Any buffs or debuffs will be left intact.

Parameters

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
effect_name String Identifier of the status ailment to apply to an entity attacked by this entity's melee attack
effect_duration Decimal 0.0 Duration in seconds of the status ailment applied to the damaged entity
Back to top

minecraft:collision_box

Controls the collision box of the entity. When changes to the component are applied the entity's collision box is immediately updated to reflect the new dimensions. WARNING: If the change of the collision box dimensions would cause the entity to be inside a block, the entity might become stuck there and start suffocating.

Parameters

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

minecraft:damage_sensor

Defines an array of damages and how the entity reacts to them - including whether the entity ignores that damage or not. Currently Minecraft triggers can't be properly serialized so any existing triggers will be completely replaced when applyComponentChanges().

Parameters

Name Type Default Value Description
on_damage List List of triggers with the events to call when taking this specific kind of damage, allows specifying filters for entity definitions and events
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
cause String Type of damage that triggers this set of events
Back to top

minecraft:equipment

Defines the loot table the entity uses to defines its equipment. Once the changes are applied, the equipment is re-rolled and a new set of equipment is chosen for the entity.

Parameters

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

minecraft:equippable

Defines how many and what items the entity can be equipped with.

Parameters

slots

List of slots and the item that can be equipped

Parameters

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
Back to top



minecraft:explode

Controls the entity's explosion, timer until the explosion, and whether the timer is counting down or not.

Parameters

Name Type Default Value Description
fuseLength 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
power Decimal 3.0 The radius of the explosion in blocks and the amount of damage the explosion deals
maxResistance Decimal Infinite A blocks explosion resistance will be capped at this value when an explosion occurs
fuseLit Boolean false If true, the fuse is already lit when this component is added to the entity
causesFire Boolean false If true, blocks in the explosion radius will be set on fire
breaks_blocks Boolean true If true, the explosion will destroy blocks in the explosion radius
fireAffectedByGriefing Boolean false If true, whether the explosion causes fire is affected by the mob griefing game rule
destroyAffectedByGriefing Boolean false If true, whether the explosion breaks blocks is affected by the mob griefing game rule
Back to top

minecraft:healable

Defines how the entity can be healed by the player. This doesn't control how much health the entity can have; you must use the Health component for that instead.

Parameters

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

minecraft:health

Defines the current and maximum possible health of the entity. Upon applying the component back to the entity the health will change. If it reaches 0 or below the entity will die.

Parameters

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

minecraft:interact

Defines the ways the player can interact with the entity to which this component is applied.

Parameters

Name Type Default Value Description
spawn_entities Array An array of entity identifiers to spawn when the interaction occurs
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_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
particle_offset_towards_interactor Boolean false Whether or not the particle will appear closer to who performed the interaction
cooldown Decimal 0.0 Time in seconds before this entity can be interacted with again
swing Boolean false If true, the player will do the 'swing' animation when interacting with this entity
use_item Boolean false If true, the interaction will use an item
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
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
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
transform_to_item String The item used will transform to this item upon successful interaction. Format: itemName:auxValue
play_sounds Array An array of sound identifiers to play when the interaction occurs
Back to top

minecraft:inventory

Defines the entity's inventory (size, restrictions, etc.). Currently this does not allow changing the entity's inventory contents.

Parameters

Name Type Default Value Description
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
can_be_siphoned_from Boolean false If true, the contents of this inventory can be removed by a hopper
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
additional_slots_per_strength Integer 0 Number of slots that this entity can gain per extra strength
Back to top

minecraft:lookat

Makes the entity look at another entity. Once applied, if an entity of the specified type is nearby and can be targeted the entity will turn towards it.

Parameters

Name Type Default Value Description
filters Minecraft Filter player Defines the entities that can trigger this component
look_cooldown Range [a, b] [0.0, 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
mAllowInvulnerable Boolean false If true, invulnerable entities (e.g. Players in creative mode) are considered valid targets
searchRadius Decimal 10.0 Maximum distance this entity will look for another entity looking at it
setTarget Boolean true If true, this entity will set the attack target as the entity that looked at it
Back to top

minecraft:nameable

Nameable component describes an entity's ability to be named using a nametag and whether the name shows up or not once applied. Additionally, scripting allows setting the name of the entity directly with the property 'name'.

Parameters

Name Type Default Value Description
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
on_named String Event to be called when this entity acquires the name specified in 'name_filter'
name_filter List List of special names that will cause the events defined in 'on_named' to fire
default_trigger String Trigger to run when the entity gets named
alwaysShow Boolean false If true, the name will always be shown
allowNameTagRenaming Boolean true If true, this entity can be renamed with name tags
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
Back to top

minecraft:position

This component allows you to control an entity's current position in the world. Once applied the entity will be teleported to the new position specified.

Parameters

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
Back to top

minecraft:rotation

This component allows you to control an entity's current rotation in the world as well as the entity's head rotation. Once applied, the entity will be rotated as specified.

Parameters

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
Back to top

minecraft:shooter

Defines the entity's ranged attacks. This doesn't allow the entity to use a ranged attack: it only defines what kind of projectile it shoots.

Parameters

Name Type Default Value Description
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
auxVal Integer -1 ID of the Potion effect to be applied on hit
Back to top

minecraft:spawn_entity

Controls the entity's ability to spawn an entity or an item. This is similar to the chicken's ability to lay eggs after a set amount of time.

Parameters

Name Type Default Value Description
min_wait_time Integer 300 Minimum amount of time to randomly wait in seconds before another entity is spawned
max_wait_time Integer 600 Maximum amount of time to randomly wait in seconds before another entity is spawned
spawn_sound String plop Identifier of the sound effect to play when the entity is spawned
spawn_item String egg Item identifier of the item to spawn
spawn_entity String Identifier of the entity to spawn, leave empty to spawn the item defined above instead
spawn_method String born Method to use to spawn the entity
spawn_event String minecraft:entity_born Event to call when the entity is spawned
Back to top

minecraft:teleport

This controls the entity's ability to teleport itself (similar to the Enderman). If you wish to teleport the entity once use the Position component instead.

Parameters

Name Type Default Value Description
darkTeleportChance Decimal 0.01 Modifies the chance that the entity will teleport if the entity is in darkness
lightTeleportChance Decimal 0.01 Modifies the chance that the entity will teleport if the entity is in daylight
maxRandomTeleportTime Decimal 20.0 Maximum amount of time in seconds between random teleports
minRandomTeleportTime Decimal 0.0 Minimum amount of time in seconds between random teleports
randomTeleportCube Vector [a, b, c] [32.0, 16.0, 32.0] Entity will teleport to a random position within the area defined by this cube
randomTeleports Boolean true If true, the entity will teleport randomly
targetDistance Decimal 16.0 Maximum distance the entity will teleport when chasing a target
target_teleport_chance Decimal 1.0 The chance that the entity will teleport between 0.0 and 1.0. 1.0 means 100%
Back to top





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

Back to top

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

The following Minecraft events are events the Script Engine is listening for and to which you can react in scripts.

minecraft:client_entered_world

This event is fired whenever a player joins the world. The event data contains the ID of the player in the world. The ID uniquely identifies the player in the world. This does NOT uniquely identify the player if they disconnect and reconnect.
Back to top

minecraft:hit_result_changed

This event is triggered whenever the reticle changes from pointing at a block or air to pointing at an entity and the other way around. Up to 1000 blocks away.

Parameters

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

Code Example:





Back to top

minecraft:hit_result_continuous

This event is triggered every update and tells you what entity the reticle is pointing to in the world up to 1000 blocks away.

Parameters

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

Code Example:





Back to top

minecraft:pick_hit_result_changed

This event is triggered whenever the mouse pointer changes from pointing at a block or air to pointing at an entity and the other way around. Up to 1000 blocks away.

Parameters

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

Code Example:





Back to top

minecraft:pick_hit_result_continuous

This event is triggered every update and tells you what entity the mouse pointer is pointing to in the world up to 1000 blocks away.

Parameters

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

Code Example:





Back to top



Trigger-able Events

The following Minecraft Events can be triggered from scripting and cause the game to respond accordingly.

minecraft:display_chat_event

This event is used to display a chat message to the specific player that is running the client script. The event data is the message to be displayed in plain text. Special formatting is supported the same way it would be if a player was sending the message.
Back to top

minecraft:execute_command

This event is used to run a slash command from the specific player running the client script. The script runs it as that player. The event data contains the slash command in plain text. The slash command will be run immediately after the event is triggered.
Back to top

minecraft:load_ui

This event is used to show a UI screen to the specific player running the client script. This event will add the UI screen to the top of the UI screen stack. The event data contains the file path to the screen's HTML file as a string. The screen will be shown immediately after the event is triggered. Only screens defined in a HTML file can be shown using this event.
Back to top

minecraft:send_ui_event

This event is used to send UI events to the UI Engine for the specific player running the script. After the event is triggered, the UI event will be sent immediately.
Custom UI is based on HTML 5. Review the scripting demo for an example of a custom UI file.

Parameters

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

minecraft:spawn_particle_attached_entity

This event is used to create a particle effect that will follow an entity around. This particle effect is only visible to the specific player that is running the client script where you fired the event. Any effect defined in a JSON file (both in your resource pack and in Minecraft) can be used here. MoLang variables defined in the JSON of the effect can then be used to control that effect by changing them in the entity to which it is attached.

Parameters

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 JavaScript 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
Back to top

minecraft:spawn_particle_in_world

This event is used to create a static particle effect in the world. This particle effect is only visible to the specific player that is running the client script where you fired the event. Any effect defined in a JSON file (both in your resource pack and in Minecraft) can be used here. Once the effect is spawned you won't be able to control it further. Unlike the server version of the event, the client version will spawn the particle in the dimension the player is currently in.

Parameters

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
Back to top

minecraft:unload_ui

This event is used to remove a UI screen from the stack of the specific player running the client script. The event data contains the name of the screen to remove as a string. After the event is triggered the screen will be scheduled to be removed from the stack the next time the UI Engine can do so. Only screens defined in a HTML file can be removed using this event.
Back to top





Server Events

Listening Events

The following Minecraft events are events the Script Engine is listening for and to which you can react in scripts.

minecraft:entity_created

This event is triggered whenever an entity is added to the world.

Parameters

Name Type Description
entity JavaScript Object The entity that was just created
Back to top

minecraft:entity_death

This event is triggered whenever an entity dies. This won't be triggered when an entity is removed (such as when using destroyEntity).

Parameters

Name Type Description
entity JavaScript Object The entity that died
Back to top

minecraft:entity_start_riding

This event is triggered whenever an entity becomes a rider on another entity.

Parameters

Name Type Description
entity JavaScript Object The rider
ride JavaScript Object The entity being ridden
Back to top

minecraft:entity_stop_riding

This event is triggered whenever an entity stops riding another entity.

Parameters

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

minecraft:entity_tick

This event is triggered whenever an entity is ticked. This event will not fire when a player is ticked.

Parameters

Name Type Description
entity JavaScript Object The entity that was ticked
Back to top

minecraft:player_attacked_actor

This event is triggered whenever a player attacks an entity.

Parameters

Name Type Description
player JavaScript Object The player that attacked an entity
attacked_entity JavaScript Object The entity that was attacked by the player
Back to top



Trigger-able Events

The following Minecraft events can be triggered from scripting and the game will respond, accordingly.

minecraft:display_chat_event

This event is used to send a chat message from the server to the players. The event data is the message being sent as a string. Special formatting is supported the same way it would be if a player was sending the message.
Back to top

minecraft:execute_command

This event is used to execute a slash command on the server with the World Owner permission level. The event data contains the slash command as a string. The slash command will be processed and will run after the event is sent.
Back to top

minecraft:spawn_particle_attached_entity

This event is used to create a particle effect that will follow an entity around. This particle effect is visible to all players. Any effect defined in a JSON file (both in your resource pack and in Minecraft) can be used here. MoLang variables defined in the JSON of the effect can then be used to control that effect by changing them in the entity to which it is attached.

Parameters

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 JavaScript 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
Back to top

minecraft:spawn_particle_in_world

This event is used to create a static particle effect in the world. This particle effect is visible to all players. Any effect defined in a JSON file (both in your resource pack and in Minecraft) can be used here. Once the effect is spawned you won't be able to control it further.

Parameters

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
Back to top