The scaffold comes with a set of pre-defined scripts on the root and on a per-package basis.
Starts the development server and a file-watcher mode in all packages to automatically re-compile on changes.
Builds the whole project in production settings (E.g. code minification enabled).
Starts the production server. This command expects that all packages have been built already.
Removes all build artifacts and dependencies (e.g. like node_modules and the flow-typed/npm typings).
Sets up the project depending on the environment.
Executes all tests of the project asynchronously (including the generation of coverage information).
All of the remaining scripts will mostly be propagated to all packages asynchronously.
You can execute most of the scripts you will find in the root also on a per-package basis. This is especially useful to restrict the output to packages that you are actively working on.
The most important script you will need while working with the scaffold is yarn run jest:watch. This spawns a file-watcher to re-run the unit-tests of the package once a file has changed. It's one of the few scripts that we cannot execute in parallel for all package via the root and the reason is pretty simple:
To keep the developer experience high we use a feature of Jest that is called Snapshot Testing, once your snapshot tests fail and you need to update them, the Jest CLI expects you to interact with it via key presses, e.g. Press "u" to update all failing snapshots and since lerna spawns sub-processes the keyboard inputs are not propagated from your root shell into the sub-processes.
For a full list of scripts on a per-package basis, please refer to the package.json scripts section.