@storybook/react/dist/modern/server/framework-preset-cra.js

Storybook for React: Develop React Component in isolation with Hot Reloading.

import { logger } from '@storybook/node-logger';
import { isReactScriptsInstalled } from './cra-config';

var checkForNewPreset = function (presetsList) {
  var hasNewPreset = presetsList.some(function (preset) {
    var presetName = typeof preset === 'string' ? preset : preset.name;
    return /@storybook(\/|\\)preset-create-react-app/.test(presetName);
  });

  if (!hasNewPreset) {
    logger.warn('Storybook support for Create React App is now a separate preset.');
    logger.warn('To use the new preset, install `@storybook/preset-create-react-app` and add it to the list of `addons` in your `.storybook/main.js` config file.');
    logger.warn('The built-in preset has been disabled in Storybook 6.0.');
  }
};

export function webpackFinal(config, {
  presetsList: presetsList
}) {
  if (isReactScriptsInstalled()) {
    checkForNewPreset(presetsList);
  }

  return config;
}