storybook/docs/_snippets/main-config-preview-body.md

export default {
  // Replace your-framework with the framework you are using (e.g., react-webpack5, vue3-vite)
  framework: '@storybook/your-framework',
  stories: ['../src/**/*.mdx', '../src/**/*.stories.@(js|jsx|mjs|ts|tsx)'],
  previewBody: (body) => `
    ${body}
    ${
      process.env.ANALYTICS_ID ? '<script src="https://cdn.example.com/analytics.js"></script>' : ''
    }
  `,
};

// Replace your-framework with the framework you are using (e.g., react-webpack5, vue3-vite)
import type { StorybookConfig } from '@storybook/your-framework';

const config: StorybookConfig = {
  framework: '@storybook/your-framework',
  stories: ['../src/**/*.mdx', '../src/**/*.stories.@(js|jsx|mjs|ts|tsx)'],
  previewBody: (body) => `
    ${body}
    ${
      process.env.ANALYTICS_ID ? '<script src="https://cdn.example.com/analytics.js"></script>' : ''
    }
  `,
};

export default config;