flow-scripts

Flow Scripts

Utility tools for Flow.

Installation

$ npm install flow-scripts --save-dev

Stub

$ flow-scripts stub

By default, running Flow on startup will read all the files under node_modules. Ignoring the node_modules directory isn't a good idea because Flow looks in there to a) ensure you've actually installed your dependencies and b) find Flow libdefs for packages which might have included them, and Flow will throw a module not found error. Refer to this issue for an in-depth discussion on the topic.

The workaround is to ignore the node_modules directory but manually include the libdefs inside the flow-typed directory or provide a stub for it. This script automatically generates the stubs required for the dependencies in package.json that are missing in the libdefs fetched from the flow-typed install command.

By adding the script to an npm script postinstall hook, when new packages are installed, it will be automatically added into flow-typed/.

In package.json, add to the postinstall hook:

  ...
  "scripts": {
    "postinstall": "flow-scripts stub"
  },
  ...

In the project directory, run:

$ flow-typed install
$ flow-scripts stub

This will do the following:

• Look up the flow-typed repo for compatible libdefs and downloade them. Detailed explanation can be found on the Flow website.
• Generates the stubs required for the dependencies in package.json that are missing in the libdefs fetched from the flow-typed install command and write them into flow-typed/package-dep-libdefs.js.

Development

Testing this library is tricky because it relies on a real project that has multiple dependencies in package.json. Hence we create a mock project in the test-project folder that has some common JS dependencies defined and symlink the flow-scripts library within that project to our development file in the root folder. Run the commands within that mock project to test that the library is actually working as intended.

$ cd test-project
$ npm install # or yarn install
$ npm link ../
$ flow-scripts stub # flow-typed/package-dep-libdefs.js file should be generated