The CKEditor 5 codebase is divided into multiple npm packages, each developed in a separate Git repository. The main package is
ckeditor5 which installs all project dependencies and various development-related resources such as:
- the testing environment setup,
- configuration for Mr. Git (a multi-repo management tool) and Yarn (a dependency management tool),
- translation management tools,
- documentation generator,
- and release tools.
You can find all the official packages listed in CKEditor 5 development repository’s README.
In order to start developing CKEditor 5 you will require:
# Setting up the CKEditor development environment
First, you need to install a couple of tools which you will be using later:
It is best to install them globally in your system for an easier use later on:
npm install -g yarn mrgit
Note: Read how to avoid using
sudo to install packages globally or use nvm.
Then clone the main repository:
git clone https://github.com/ckeditor/ckeditor5.git cd ckeditor5
And install all CKEditor 5 packages from the npm registry.
Note: If you plan to use the developement version of CKEditor 5 packages (see the next section), you can skip this step to save time.
# Switching to development version of packages
The steps above should install all the packages from npm, which means that you will have the latest releases of all of them. They are available in
node_modules/@ckeditor/ (we are using scoped packages, hence the unusual directory).
In order to work with development versions of all the official packages, it is recommended to use
mrgit. This tool will clone all package repositories to the
packages/ directory. Then, those packages need to be installed in a way understandable by Node.js-compliant tools (like webpack or Browserify). In order to achieve that we use Yarn’s feature called workspaces which creates symlinks to these packages.
First, clone all the repositories:
(master 340feac) p@m /workspace/ckeditor5> tree -L 1 packages/ packages/ ├── ckeditor5-autoformat ├── ckeditor5-basic-styles ├── ckeditor5-clipboard ... └── ckeditor5-utils
Finally, install all external dependencies (such as the test runner) and create symlinks to CKEditor 5 packages available in the
packages/ directory with this one command:
You can check that CKEditor 5 packages which are part of the development environment (so those except development tools and some closed source packages) should be linked:
(master ae6f43a) p@m /workspace/misc/ckeditor5> ls -la node_modules/\@ckeditor/ total 0 drwxr-xr-x 54 p staff 1728 11 sty 14:41 . drwxr-xr-x 1115 p staff 35680 11 sty 14:41 .. drwxr-xr-x 7 p staff 224 11 sty 14:41 ckeditor-cloud-services-collaboration drwxr-xr-x 6 p staff 192 11 sty 14:41 ckeditor-cloud-services-core lrwxr-xr-x 1 p staff 41 11 sty 14:41 ckeditor5-adapter-ckfinder -> ../../packages/ckeditor5-adapter-ckfinder lrwxr-xr-x 1 p staff 34 11 sty 14:41 ckeditor5-alignment -> ../../packages/ckeditor5-alignment lrwxr-xr-x 1 p staff 35 11 sty 14:41 ckeditor5-autoformat -> ../../packages/ckeditor5-autoformat lrwxr-xr-x 1 p staff 33 11 sty 14:41 ckeditor5-autosave -> ../../packages/ckeditor5-autosave lrwxr-xr-x 1 p staff 37 11 sty 14:41 ckeditor5-basic-styles -> ../../packages/ckeditor5-basic-styles lrwxr-xr-x 1 p staff 36 11 sty 14:41 ckeditor5-block-quote -> ../../packages/ckeditor5-block-quote lrwxr-xr-x 1 p staff 38 11 sty 14:41 ckeditor5-build-balloon -> ../../packages/ckeditor5-build-balloon lrwxr-xr-x 1 p staff 38 11 sty 14:41 ckeditor5-build-classic -> ../../packages/ckeditor5-build-classic lrwxr-xr-x 1 p staff 49 11 sty 14:41 ckeditor5-build-decoupled-document -> ../../packages/ckeditor5-build-decoupled-document lrwxr-xr-x 1 p staff 37 11 sty 14:41 ckeditor5-build-inline -> ../../packages/ckeditor5-build-inline lrwxr-xr-x 1 p staff 33 11 sty 14:41 ckeditor5-ckfinder -> ../../packages/ckeditor5-ckfinder lrwxr-xr-x 1 p staff 34 11 sty 14:41 ckeditor5-clipboard -> ../../packages/ckeditor5-clipboard lrwxr-xr-x 1 p staff 39 11 sty 14:41 ckeditor5-cloud-services -> ../../packages/ckeditor5-cloud-services drwxr-xr-x 7 p staff 224 11 sty 14:41 ckeditor5-collaboration-core drwxr-xr-x 7 p staff 224 11 sty 14:41 ckeditor5-comments lrwxr-xr-x 1 p staff 29 11 sty 14:41 ckeditor5-core -> ../../packages/ckeditor5-core drwxr-xr-x 8 p staff 256 11 sty 14:41 ckeditor5-dev-docs drwxr-xr-x 9 p staff 288 11 sty 14:41 ckeditor5-dev-env drwxr-xr-x 9 p staff 288 11 sty 14:41 ckeditor5-dev-tests drwxr-xr-x 8 p staff 256 11 sty 14:41 ckeditor5-dev-utils drwxr-xr-x 8 p staff 256 11 sty 14:41 ckeditor5-dev-webpack-plugin lrwxr-xr-x 1 p staff 35 11 sty 14:41 ckeditor5-easy-image -> ../../packages/ckeditor5-easy-image lrwxr-xr-x 1 p staff 39 11 sty 14:41 ckeditor5-editor-balloon -> ../../packages/ckeditor5-editor-balloon lrwxr-xr-x 1 p staff 39 11 sty 14:41 ckeditor5-editor-classic -> ../../packages/ckeditor5-editor-classic lrwxr-xr-x 1 p staff 41 11 sty 14:41 ckeditor5-editor-decoupled -> ../../packages/ckeditor5-editor-decoupled lrwxr-xr-x 1 p staff 38 11 sty 14:41 ckeditor5-editor-inline -> ../../packages/ckeditor5-editor-inline lrwxr-xr-x 1 p staff 31 11 sty 14:41 ckeditor5-engine -> ../../packages/ckeditor5-engine lrwxr-xr-x 1 p staff 30 11 sty 14:41 ckeditor5-enter -> ../../packages/ckeditor5-enter ... and so on
If everything worked correctly, you should be able to run some tests:
yarn run test --files=core
# Fetching changes
Whenever you want to update all packages to their latest versions call:
# To update the ckeditor5 repository itself: git pull # To update pull changes to all the packages: mrgit sync # To install missing dependencies: yarn install
From time to time, if the list of dependencies in any of the packages changed, new package has been added to
ckeditor5 or you just want to make sure that you have the repository up to date, run the
git pull yarn run reinstall
reinstall script first calls
yarn run clean to remove
node_modules/ directories from all packages (including
ckeditor5) and then
yarn run bootstrap which is a shorthand for
mrgit sync && yarn install.
# Working with multiple repositories
Mr. Git implements many useful commands, such as:
mrgit exec 'command'– executing a shell command in all repositories,
mrgit checkout <branch>– checking all repositories to given branch (or hash),
mrgit status– displaying information about all repositories.
Read more about those commands in mrgit’s documentation.
mrgit for custom packages
If you are developing custom packages or forked any of the official packages and want
mrgit to work with it, change the dependencies configuration in
mrgit.json. Note that
mrgit is able to clone the package from any Git URL. Refer to its documentation for more details.
# Running tests
In order to run tests you need to use the
yarn run test --watch --coverage --source-map --files=engine
yarn run test -- -wcs --files=engine
This command will run the
ckeditor5-engine package’s tests.
Note: It is not possible to run tests of all packages with code coverage at once because the size of the project (the number of test files and source modules) exceeds webpack’s capabilities (it runs out of memory).
To create a server for manual tests use the
yarn run manual
It accepts the
You can read more about the Testing environment.
# Generating documentation
To build the documentation you need to run the
yarn run docs
The documentation will be available in
This task accepts the following arguments:
--skip-api— Skips building the API documentation (which takes the majority of the total time).
--skip-snippets— Skips building live snippets.
--snippets=snippet-name— Whitelist snippets to build (accepts glob patterns).
--skip-validation— Skips the final link validation.
--watch— Runs the documentation generator in a watch mode. It covers guides (it does not cover API docs).
--production— Minifies the assets and performs other actions which are unnecessary during CKEditor 5 development.
--verbose— Prints out more information.
Note: These arguments must be passed after additional
yarn run docs --skip-api
# Generating content styles
It is possible to generate a stylesheet containing content styles brought by all CKEditor 5 features. In order to do that, execute:
The stylesheet will be saved in the
To learn more, refer to the Content styles guide.
# Bisecting through a multi-repository
CKEditor 5 is a multi-repository project. It means that
git bisect (which is super handy when tracking which commit introduced a bug) will not work out of the box.
Fortunately, every commit made to any of the
master branches of all CKEditor 5 subpackages will update this subpackage’s hash in
mrgit.json in the
Thanks to that,
master-revisions contains an ordered history of all changes which makes it possible to go back to any point in history:
# Make sure to update this branch. git co master-revisions git pull # Check out 30 commits back. git co master-revisions~30 # Check out subpackages to correct hashes. mrgit co
Once you found the point in history which interests you, you can go straight to a commit in a subpackage and PR. For example:
(detached:bisect/bad~1 cb2feef ?1) p@m /workspace/ckeditor5> git bisect good ab5b5494e5eba7beb4a3bac4ea9c5e6d59a610f5 is the first bad commit commit ab5b5494e5eba7beb4a3bac4ea9c5e6d59a610f5 Author: Travis CI User <firstname.lastname@example.org> Date: Tue Apr 11 16:45:47 2017 +0000 Revision: https://github.com/ckeditor/ckeditor5-image/commit/02869eb4478a2f538006c128b30b9727617af665 :100644 100644 611526d5c4beae7046b0a08ec36843cbbe642175 35acdd8ba971d8127dd462a9c8c1162a54f00d58 M mgit.json
# Additional information for contributors
# SVG icons
By default, CKEditor 5 supports SVG icons found in the
ckeditor5-*/theme/icons folders. Unfortunately, most of the SVG editing software produces the output with comments, obsolete tags, and complex paths, which bloats the DOM and makes the builds heavy for no good reason.
To remove the excess data and prevent certain issues, all new icons should be optimized before joining the code base. To do that, you can use the
clean-up-svg-icons script in the root of the project, a wrapper for the SVGO tool:
cd path/to/ckeditor5 # Optimize all SVG files in the folder. npm run clean-up-svg-icons path/to/icons/*.svg # Optimize a single SVG file. npm run clean-up-svg-icons path/to/icon/icon.svg
The script reduces the icon size up to 70%, depending on the software used to create it and the general complexity of the image.
Note: You may still need to tweak the source code of the SVG files manually after using the script:
- The icons should have the
viewBoxattribute (instead of
removeDimensionsSVGO plugin will not remove
heightif there is no
viewBoxattribute so make sure it is present.
- Sometimes SVGO leaves empty (transparent) groups
<g>...</g>. They should be removed from the source.
- Make sure the number of
<path>elements is minimal. Merge paths whenever possible in the image processor before saving the file.