Code.org fork of google/blockly for use within the Code Studio learning environment.


stars 🌟issues ⚠️updated 🛠created 🐣size 🏋️‍♀️
4537Jul 29, 2021Aug 29, 2016Minified + gzip package size for @code-dot-org/blockly in KB


Blockly (Code Studio fork)

npm version CircleCI

This is a fork of Blockly, an open source visual programming environment.

Major additions and changes in this fork:

  • Modal editor for function blocks (function_editor.js)
  • Scrolling improvements:
  • New in-toolbox trashcan
  • Addition of "Functional blocks" and "Contract/Variable Editor" (contract_editor/) for use in the CS in Algebra curriculum
  • Support for "block limits" (block_limits.js), toolbox blocks which allow only a certain number of instances in the block space
  • Support for new block properties (block.js): invisible, un-deletable, immovable, specify-able via a context menu when Blockly.editBlocks is set
  • Structure: add folders in core/ to further categorize classes
  • New field types:
  • BlockSpace (Workspace) Refactoring:
    • moved many static properties and methods from blockly.js into a prototype class BlockSpaceEditor which can be instantiated multiple times on the same page
    • renamed Workspace to BlockSpace to disambiguate from higher-level BlockSpaceEditor
    • improved support for multiple blockspaces on a single page
  • Playground: add dependency cache and generation script (tests/update_test_dependencies.sh), to allow for testing changes without re-building
    • support for goog.ui.tweaks to configure playground page behavior
    • debug drawing helpers for block bumping
  • Support for a special UI for unattached blocks
  • Improvements to block arrangement on initialization
  • Testing: add phantomjs-based test runner test.sh. Tested in CI at root level of this repository.


  1. Download and install JDK version 8 from here
  2. run the following commands:
cd blockly
npm install
npm run build


Playground manual testing page

There is a playground manual testing page at tests/playground.html, which requires no build step or server running.

open tests/playground.html

Building with apps

This is the most typical use case for code-dot-org fork development.

Apps (aka Code Studio) is a set of blockly apps built on top of blockly, which installs and references this package via NPM. The easiest pathway for local development is to use npm-link:

cd {blockly repo directory}
npm link
cd {code-dot-org repo directory}/apps
npm link @code-dot-org/blockly

Apps will now reference your local blockly repository rather than the npm package. If you then make local changes to your repo, you can simply rebuild blockly (via npm run build in this repo) and then apps (via npm run build in code-dot-org/apps) to communicate those changes to apps.

Publishing changes

To publish a new version to npm switch to the main branch, use npm login to sign in as an account with access to the @code-dot-org scope, then npm version [major|minor|patch|premajor|preminor|prepatch] for the appropriate version bump. This will do the following:

  • Run linting and tests to verify your local repo.
  • Rebuild the release package.
  • Bump the version, adding a corresponding commit and version tag.
  • Push the commit and tag to github.
  • Publish the new release package to npm.

Testing changes

There are a set of utility and integration tests included in tests/blockly_test.html, and a playground manual testing page at tests/playground.html.

After adding any new files, you will need to run ./update_test_dependencies.sh to update the test dependency map, which caches file dependencies so edits can be tested and played with without any re-build time.

There are three ways the test suites can be run:

  1. ./test.sh will run the tests in phantomjs
  2. To debug failures, you can open the test page in your browser, e.g. open tests/blockly_test.html
  3. ./deploy.sh will also run ./test.sh at the end of its full rebuild.
Other tests covering this package

Blockly apps contains many tests that target features of blockly in the context of the code.org curriculum apps.

Additionally, Dashboard's UI tests cover certain features of blockly through Cucumber / Selenium scenarios.

If you find any bugs or have a feature request, please open an issue on github!

The npm package download data comes from npm's download counts api and package details come from npms.io.