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Roll Stimulus.js applications, including autoloading of controllers.

npm install --save-dev rollup-plugin-stimulus

In addition to installing the plugin, you will likely want to install stimulus so you can initialize the application. You will also likely want to use rollup-plugin-node-resolve if you install Stimulus via npm.

npm install --save-dev stimulus
npm install --save-dev rollup-plugin-node-resolve 

Configure your Rollup bundle to initialize the rollup-plugin-stimulus and resolve plugins:

// rollup.config.js
import resolve from 'rollup-plugin-node-resolve';
import stimulus from 'rollup-plugin-stimulus';

export default [{
  input: 'src/app.js',
  output: {
    file: 'dist/app.js',
    format: 'esm',
    sourcemap: true,
  },
  plugins: [
    stimulus(),
    resolve(),
  ],
}];

Loading rollup-plugin-stimulus gives you access to a stimulus-controllers import in your app source code. The stimulus-controllers import provides an array of controller definitions that you can pass to Stimulus' application.load method.

// src/app.js
import { Application } from 'stimulus';
import controllers from 'stimulus-controllers';

const application = Application.start();
application.load(controllers);

This will initialize a Stimulus app with any controllers named [identifier]_controller.js found in the controllers directory at the same level of your Rollup input file. For example, if your Rollup input is src/app.js, files named [identifier]_controller.js will be looked for in src/controllers and all subdirectories.

Controllers' data-controller identifiers follow the conventions discussed in the Stimulus Handbook. The file name identifier is converted to a data-controller identifier by replacing underscores with a dash (-) and diretory separators (i.e. /) with double dashes (--).

As taken from the Stimulus manual:

While rollup-plugin-stimulus is designed to work without configuration, there are some options you can configure:

// rollup.config.js
import resolve from 'rollup-plugin-node-resolve';
import stimulus from 'rollup-plugin-stimulus';

export default [{
  input: 'src/app.js',
  output: {
    file: 'dist/app.js',
    format: 'esm',
    sourcemap: true,
  },
  plugins: [
    stimulus({
      // the directory your controllers are stored in
      basePath: './src/controllers',

      // the name that is used to import Stimulus controllers in the app
      importName: 'stimulus-controllers',

      // whether or not to show 'this is undefined' warnings when importing @stimulus modules
      showWarnings: false,
    }),
    resolve(),
  ],
}];