0.1.6 • Public • Published


Scratch GUI is a set of React components that comprise the interface for creating and running Scratch 3.0 projects

Build Status Greenkeeper badge


This requires you to have Git and Node.js installed.

In your own node environment/application:

npm install

If you want to edit/play yourself:

git clone
cd scratch-gui
npm install

You may want to add --depth=1 to the git clone command because there are some large files in the git repository history.

Getting started

Running the project requires Node.js to be installed.


Open a Command Prompt or Terminal in the repository and run:

npm start

Then go to http://localhost:8601/ - the playground outputs the default GUI component

Developing alongside other Scratch repositories

Getting another repo to point to this code

If you wish to develop scratch-gui alongside other scratch repositories that depend on it, you may wish to have the other repositories use your local scratch-gui build instead of fetching the current production version of the scratch-gui that is found by default using npm install.

Here's how to link your local scratch-gui code to another project's node_modules/scratch-gui.


  1. In your local scratch-gui repository's top level:

    1. Make sure you have run npm install
    2. Build the dist directory by running BUILD_MODE=dist npm run build
    3. Establish a link to this repository by running npm link
  2. From the top level of each repository (such as scratch-www) that depends on scratch-gui:

    1. Make sure you have run npm install
    2. Run npm link scratch-gui
    3. Build or run the repositoriy

Using npm run watch

Instead of BUILD_MODE=dist npm run build, you can use BUILD_MODE=dist npm run watch instead. This will watch for changes to your scratch-gui code, and automatically rebuild when there are changes. Sometimes this has been unreliable; if you are having problems, try going back to BUILD_MODE=dist npm run build until you resolve them.

Oh no! It didn't work!

If you can't get linking to work right, try:

  • Follow the recipe above step by step and don't change the order. It is especially important to run npm install before npm link, because installing after the linking will reset the linking.
  • Make sure the repositories are siblings on your machine's file tree, like .../.../MY_SCRATCH_DEV_DIRECTORY/scratch-gui/ and .../.../MY_SCRATCH_DEV_DIRECTORY/scratch-www/.
  • Consistent node.js version: If you have multiple Terminal tabs or windows open for the different Scratch repositories, make sure to use the same node version in all of them.
  • If nothing else works, unlink the repositories by running npm unlink in both, and start over.



You may want to review the documentation for Jest and Enzyme as you write your tests.

See jest cli docs for more options.

Running tests

NOTE: If you're a windows user, please run these scripts in Windows cmd.exe instead of Git Bash/MINGW64.

Before running any tests, make sure you have run npm install from this (scratch-gui) repository's top level.

Main testing command

To run linter, unit tests, build, and integration tests, all at once:

npm test

Running unit tests

To run unit tests in isolation:

npm run test:unit

To run unit tests in watch mode (watches for code changes and continuously runs tests):

npm run test:unit -- --watch

You can run a single file of integration tests (in this example, the button tests):

$(npm bin)/jest --runInBand test/unit/components/button.test.jsx

Running integration tests

Integration tests use a headless browser to manipulate the actual html and javascript that the repo produces. You will not see this activity (though you can hear it when sounds are played!).

Note that integration tests require you to first create a build that can be loaded in a browser:

npm run build

Then, you can run all integration tests:

npm run test:integration

Or, you can run a single file of integration tests (in this example, the backpack tests):

$(npm bin)/jest --runInBand test/integration/backpack.test.js

If you want to watch the browser as it runs the test, rather than running headless, use:

USE_HEADLESS=no $(npm bin)/jest --runInBand test/integration/backpack.test.js


Ignoring optional dependencies

When running npm install, you can get warnings about optionsl dependencies:

npm WARN optional Skipping failed optional dependency /chokidar/fsevents:
npm WARN notsup Not compatible with your operating system or architecture: fsevents@1.2.7

You can suppress them by adding the no-optional switch:

npm install --no-optional

Further reading: Stack Overflow

Resolving dependencies

When installing for the first time, you can get warnings which need to be resolved:

npm WARN eslint-config-scratch@5.0.0 requires a peer of babel-eslint@^8.0.1 but none was installed.
npm WARN eslint-config-scratch@5.0.0 requires a peer of eslint@^4.0 but none was installed.
npm WARN scratch-paint@0.2.0-prerelease.20190318170811 requires a peer of react-intl-redux@^0.7 but none was installed.
npm WARN scratch-paint@0.2.0-prerelease.20190318170811 requires a peer of react-responsive@^4 but none was installed.

You can check which versions are available:

npm view react-intl-redux@0.* version

You will neet do install the required version:

npm install  --no-optional --save-dev react-intl-redux@^0.7

The dependency itself might have more missing dependencies, which will show up like this:

user@machine:~/sources/scratch/scratch-gui (491-translatable-library-objects)$ npm install  --no-optional --save-dev react-intl-redux@^0.7
scratch-gui@0.1.0 /media/cuideigin/Linux/sources/scratch/scratch-gui
├── react-intl-redux@0.7.0
└── UNMET PEER DEPENDENCY react-responsive@5.0.0

You will need to install those as well:

npm install  --no-optional --save-dev react-responsive@^5.0.0

Further reading: Stack Overflow

Publishing to GitHub Pages

You can publish the GUI to so that others on the Internet can view it. Read the wiki for a step-by-step guide.

Understanding the project state machine

Since so much code throughout scratch-gui depends on the state of the project, which goes through many different phases of loading, displaying and saving, we created a "finite state machine" to make it clear which state it is in at any moment. This is contained in the file src/reducers/project-state.js .

It can be hard to understand the code in src/reducers/project-state.js . There are several types of data and functions used, which relate to each other:

Loading states

These include state constant strings like:

  • NOT_LOADED (the default state),
  • ERROR,
  • etc.


These are names for the action which causes a state change. Some examples are:


How transitions relate to loading states

As this diagram of the project state machine shows, various transition actions can move us from one loading state to another:

Project state diagram

Note: for clarity, the diagram above excludes states and transitions relating to error handling.


Here's an example of how states transition.

Suppose a user clicks on a project, and the page starts to load with url .

Here's what will happen in the project state machine:

Project state example

  1. When the app first mounts, the project state is NOT_LOADED.
  2. The SET_PROJECT_ID redux action is dispatched (from src/lib/project-fetcher-hoc.jsx), with projectId set to 123456. This transitions the state from NOT_LOADED to FETCHING_WITH_ID.
  3. The FETCHING_WITH_ID state. In src/lib/project-fetcher-hoc.jsx, the projectId value 123456 is used to request the data for that project from the server.
  4. When the server responds with the data, src/lib/project-fetcher-hoc.jsx dispatches the DONE_FETCHING_WITH_ID action, with projectData set. This transitions the state from FETCHING_WITH_ID to LOADING_VM_WITH_ID.
  5. The LOADING_VM_WITH_ID state. In src/lib/vm-manager-hoc.jsx, we load the projectData into Scratch's virtual machine ("the vm").
  6. When loading is done, src/lib/vm-manager-hoc.jsx dispatches the DONE_LOADING_VM_WITH_ID action. This transitions the state from LOADING_VM_WITH_ID to SHOWING_WITH_ID
  7. The SHOWING_WITH_ID state. Now the project appears normally and is playable and editable.


We provide Scratch free of charge, and want to keep it that way! Please consider making a donation to support our continued engineering, design, community, and resource development efforts. Donations of any size are appreciated. Thank you!




Package Sidebar


Weekly Downloads






Unpacked Size

40.5 MB

Total Files


Last publish


  • wincax8968