Minecraft Script REPL Add-On

Script REPL (read-eval-print loop) Add-On is a debugging tool for Minecraft Scripting, that allows user to run JavaScript code in Minecraft: Bedrock Edition. This powerful add-on is great to use for debugging, prototyping, and learning JavaScript and Minecraft's scripting API.

REPL Form

Currenly JavaScript is the only programming language that allow developers to use Script APIs from within their code.

This add-on allows developers to debug JavaScript code and reports an error condition immediately in Minecraft in-game using this interpreter. This reduces the amount of script errors happened in your code development and time, and allows developers to experiment with the new features available in Script API modules in Minecraft.

Learning Minecraft's Script API

You are advised to learn JavaScript free from online courses available online before learning how to use Minecraft's Scripting API, such as the following:

There are somewhat decent amount of resources available online related to script API. Important links have a ⭐.

⭐ Official Script API Documentation - Microsoft's official documentation of high-level introduction of experimental Script API
Jayly's Script API Documentation - Jayly's Script API documentation with guides and easy to use and understand API references for programming beginners.
Script API Examples - JavaScript code snippets that uses Script API modules only

Click here for a list of links related to resources for Minecraft Script API.

Add-On Usage Examples

Here are some examples executing JavaScript in-game:

This script makes the world / script engine say "running"

Example 1 code

Example 1 result

This script shows the script has error.

Example 2 code

Example 2 result

Get it? Cause Aether dimension does not exist in Minecraft.

Script REPL Item

repl item

You can get the JavaScript REPL [Use] item through the following methods:

Script event command
```
/scriptevent interpreter:js
```
Chat Command
```
!javascript
```
Important

This feature is only available behind beta versions of interpreter only.

Use the enchantment book with the name JavaScript REPL [Use] to open the interpreter
Type your javascript code in the form. Best thing is that this form has multi-line supported, meaning you can write multiple lines of code here.
Press Submit button to start executing your code.

In case you want to disable your code, you have to run /reload command which requires operator permission to execute the command.

Script Block

Note

This feature is not available to Script REPL v1.21.0 without Beta APIs experiment.

The Script Block can store and execute JavaScript code in a Minecraft world. It cannot be obtained or used in Survival mode without cheats.

Obtaining

The script blocks can either be obtained by using various commands, such as /give @s interpreter:script_block or /setblock ~ ~ ~ interpreter:script_block, or by pressing the pick block control on an existing script block.

Script blocks are not flammable, and have the same blast resistance as bedrock. They cannot cannot be mined in Survival mode, however they can be pushed with pistons and sticky pistons and the data inside the block persists.

Script Block Usage

A script block can execute JavaScript code when activated by pressure plates and buttons currently. Script output is displayed when player activates the script block.

Modification

To enter command or modify the script block, players must interact with the script block. The scripts can be entered in the text input within the modal form. The text limit for scripts in a script block is 32,767 characters, you can scroll through lines of code just like the NPC text prompt UI.

Scripts in a script block do not need to be prefixed with imports (e.g. import { world } from "@minecraft/server") as they do in the actual JavaScript files.

When finished inputing JavaScript code, save the code into the script block by pressing 'Save' button. Upon pressing the button it will not immediately execute scripts unlike the Script REPL item.

Chat Commands (Beta)

The add-on also provides chat commands that is locked behind Script REPL beta versions.

!help: Help Command
!interpreter: Opens Interpreter

This command requires operator permission.
!javascript: Opens a javascript REPL

This command requires operator permission.
!version: Displays the version of the interpreter

This command requires operator permission.

Trailer

This is a very old showcase video of the add-on, fun fact the video includes the ability to run TypeScript code because this add-on used to be able to run TypeScript code.

Installation

First you go to the download section and click "Download Script REPL" (with or without experimentals), then the add-on will be downloaded to your device.

Using Interpreter with Beta API features

Import the add-on to Minecraft.

Important

Enable Beta APIs experiments in world settings. These experiments are needed to run Script REPL with Beta API features.

experiments

Enable Experiments in New Create World Screen

Using Interpreter without Beta API features

No experimental toggles needed to be enabled.

What APIs the REPL supports

Each invidiual version of Script REPL supports various fields of the APIs. Each version of script REPL have the latest version of script modules as the dependency on their channels:

Script REPL (Latest + Beta APIs):
- @minecraft/server: 1.16.0-beta
- @minecraft/server-ui: 1.4.0-beta
- @minecraft/server-gametest: 1.0.0-beta
- @minecraft/debug-utilities: 1.0.0-beta
Script REPL (Latest):
- @minecraft/server: 1.15.0
- @minecraft/server-ui: 1.3.0
Script REPL (Preview + Beta APIs):
- @minecraft/server: 1.17.0-beta
- @minecraft/server-ui: 1.4.0-beta
- @minecraft/server-gametest: 1.0.0-beta
- @minecraft/debug-utilities: 1.0.0-beta
Script REPL (Preview):
- @minecraft/server: 1.16.0
- @minecraft/server-ui: 1.3.0
Script REPL (Preview, Bedrock Server build):
- @minecraft/server: 1.17.0-beta
- @minecraft/server-ui: 1.4.0-beta
- @minecraft/server-gametest: 1.0.0-beta
- @minecraft/debug-utilities: 1.0.0-beta
- @minecraft/server-net: 1.0.0-beta
- @minecraft/server-admin: 1.0.0-beta

Note

All versions of Script REPL also loads external npm packages such as @minecraft/vanilla-data and @minecraft/math (using v1.4.0) when executing JavaScript code.

Bedrock Dedicated Server Build

Caution

The Script REPL Add-On support for using Bedrock Dedicated Server exclusive APIs are currently experimental.

Important

This version of the Script REPL add-on do not function within the Minecraft game client or within Minecraft Realms.

The Bedrock Dedicated Server version of the Script REPL Add-On allows players to access higher levels of Script APIs, specifically the @minecraft/server-net module and the @minecraft/server-admin module. These modules are exclusive to Bedrock Dedicated Servers.

The @minecraft/server-net module can send HTTP requests from the Bedrock server, and inspect Bedrock server packets.

The @minecraft/server-admin module can administe a Bedrock Dedicated Server, including transfer players to another Bedrock server.

Enable modules in BDS

To use this add-on, you would have to enable some modules in the Bedrock Dedicated Server folder. This allows this version of the add-on to be used.

Install Bedrock Dedicated Server

If you haven't already, download the Bedrock Dedicated Server package from the Minecraft website.
Extract the zip file on a folder.

bedrock-server
│  allowlist.json
│  bedrock_server.exe
│  bedrock_server_how_to.html
│  permissions.json
│  release-notes.txt
│  server.properties
│
├─behavior_packs
├─config
│  └─default
│          permissions.json
│
├─definitions
└─resource_packs

In the permissions.json file, which is located in config/<pack_id>/permissions.json or config/default/permissions.json, enable @minecraft/server-net module, the @minecraft/server-admin module and the @minecraft/debug-utilities module by adding the following in the allowed_modules key. These module is not enabled by default in the server.

{
  "allowed_modules": [
    "@minecraft/server-gametest",
    "@minecraft/server",
    "@minecraft/server-ui",
    "@minecraft/server-admin",
+   "@minecraft/server-net",
+   "@minecraft/debug-utilities",
    "@minecraft/server-editor"
  ]
}

Full file (config/default/permissions.json):

{
  "allowed_modules": [
    "@minecraft/server-gametest",
    "@minecraft/server",
    "@minecraft/server-ui",
    "@minecraft/server-admin",
    "@minecraft/server-net",
    "@minecraft/debug-utilities",
    "@minecraft/server-editor"
  ]
}

Important

Modifying the files in the default config folder allows every add-on with the server-net module to have access to the @minecraft/server-net module.
It is recommended to assign individual permissions for each script behavior pack.

Enable Beta APIs in world settings. It's recommended to enable this setting in Minecraft clients.

experiments

Enable Beta APIs experiments in world settings. This is needed to run Script REPL with Beta API features.

Downloads

These download links do not go through Boostellar, so there shouldn't be any malicious links.

Minecraft: Bedrock Edition Preview

Minecraft: Bedrock Edition

Minecraft: Education Edition

Important

To use this add-on in Minecraft: Education Edition, experiments may be required to activate the add-on. The resource pack below allows experiments to be enabled in Education Edition.

Download Enable Experiments Resource Pack (for Minecraft Education only)

Other Versions

Click the link below and choose a version of Script REPL add-on that is compatible with your Minecraft version to download.

Download Script REPL Add-On