Shared UI Library

Shared UI Library Overview

At its core, shared ui library is about doing one thing well inside your Module Federation project. Once you understand the pattern, you can apply it consistently across features and teams.

Good shared ui library pays off across the whole codebase: fewer surprises, easier testing, and smoother onboarding. The snippet below is a solid starting point.

new ModuleFederationPlugin({
  name: 'shell',
  shared: {
    react: { singleton: true, requiredVersion: '^18.2.0' },
    'react-dom': { singleton: true, requiredVersion: '^18.2.0' },
  },
});

Marking shared libraries as singletons ensures one React instance is used across all micro frontends.

Shared UI Library Example

new ModuleFederationPlugin({
  name: 'app',
  filename: 'remoteEntry.js',
  exposes: { './Widget': './src/Widget' },
  remotes: { other: 'other@http://host/remoteEntry.js' },
  shared: { react: { singleton: true } },
});

• Start from a minimal Shared UI Library example and grow it only as needed.
• Keep configuration explicit so Shared UI Library behaves the same in every environment.
• Name things clearly so teammates understand your Shared UI Library at a glance.
• Add tests around Shared UI Library early to lock in expected behaviour.

Module Federation Cheatsheet

Key Module Federation settings related to shared ui library.

How Shared UI Library Works in Module Federation

Shared UI Library builds on Module Federation's ability to load code from another independently built and deployed application at runtime. Each app can be a host, a remote, or both.

Marking shared libraries as singletons ensures one React instance is used across all micro frontends.

• Remotes expose modules through a remoteEntry.js manifest.
• Hosts declare remotes and import exposed modules dynamically.
• Shared dependencies are deduplicated, ideally as singletons.
• Each micro frontend builds and deploys on its own schedule.

Practical Guidance for Shared UI Library

In production, shared ui library needs careful version management and graceful failure handling. Align shared dependency versions and always render a fallback when a remote cannot load.

Common Mistakes

• Copying shared ui library snippets without understanding what each line does.
• Skipping error handling and edge cases when wiring up shared ui library.
• Leaving shared ui library untested, so regressions slip into production.
• Over-engineering shared ui library before you actually need the extra flexibility.

Key Takeaways

• Shared UI Library is a core part of working effectively with Module Federation.
• Start small and keep shared ui library focused on a single responsibility.
• Apply consistent patterns so shared ui library scales across your project.
• Test and document shared ui library to keep it maintainable over time.