@storybook/addon-essentials/dist/modern/index.js

import path, { dirname, join } from 'path';
import { logger } from '@storybook/node-logger';
import { serverRequire } from '@storybook/core-common';

const requireMain = configDir => {
  var _serverRequire;

  const absoluteConfigDir = path.isAbsolute(configDir) ? configDir : path.join(process.cwd(), configDir);
  const mainFile = path.join(absoluteConfigDir, 'main');
  return (_serverRequire = serverRequire(mainFile)) !== null && _serverRequire !== void 0 ? _serverRequire : {};
};

export function addons(options = {}) {
  const checkInstalled = (addon, main) => {
    var _main$addons;

    const existingAddon = (_main$addons = main.addons) === null || _main$addons === void 0 ? void 0 : _main$addons.find(entry => {
      const name = typeof entry === 'string' ? entry : entry.name;
      return name === null || name === void 0 ? void 0 : name.startsWith(addon);
    });

    if (existingAddon) {
      logger.info(`Found existing addon ${JSON.stringify(existingAddon)}, skipping.`);
    }

    return !!existingAddon;
  };

  const main = requireMain(options.configDir);
  return ['docs', 'controls', 'actions', 'backgrounds', 'viewport', 'toolbars', 'measure', 'outline'].filter(key => options[key] !== false).map(key => `@storybook/addon-${key}`).filter(addon => !checkInstalled(addon, main)) // Use `require.resolve` to ensure Yarn PnP compatibility
  // Files of various addons should be resolved in the context of `addon-essentials` as they are listed as deps here
  // and not in `@storybook/core` nor in SB user projects. If `@storybook/core` make the require itself Yarn 2 will
  // throw an error saying that the package to require must be added as a dependency. Doing `require.resolve` will
  // allow `@storybook/core` to work with absolute path directly, no more require of dep no more issue.
  // File to load can be `preset.js`, `register.js`, or the package entry point, so we need to check all these cases
  // as it's done in `lib/core/src/server/presets.js`.
  .map(addon => {
    try {
      return dirname(require.resolve(join(addon, 'package.json'))); // eslint-disable-next-line no-empty
    } catch (err) {}

    return require.resolve(addon);
  });
}