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In Micro Frontends, different parts of your application might use the same libraries, like React, Vue, or Lodash. Without careful management, each Micro Frontend could bundle its own copy of these libraries.

This means users would download the same code multiple times, increasing load times and wasting bandwidth. Sharing dependencies solves this problem!

Imagine your main 'Host' application uses React, and a 'Remote' Micro Frontend also uses React. If both bundle React independently, your user's browser ends up downloading React twice.

• Host Bundle: Includes React
• Remote Bundle: Includes React (again!)

This leads to larger overall application sizes and slower performance.

Webpack's Module Federation offers a powerful solution: the shared configuration. It allows you to declare common libraries that should be shared across your federated applications.

Module Federation then ensures these libraries are loaded only once, even if multiple Micro Frontends depend on them.

You define shared dependencies within the ModuleFederationPlugin in your webpack.config.js file. The shared property is an object where each key is the name of a module you want to share.

Here's a basic look at how it's structured:

The requiredVersion option is crucial for compatibility. It specifies the acceptable version range for a shared dependency using semantic versioning (e.g., ^18.0.0).

Module Federation will try to use a compatible version already loaded; if none exists or it's incompatible, it will load a new one.

Normally, shared modules are loaded asynchronously, on demand. However, sometimes a shared module is needed immediately at startup, before any remote modules are even requested.

For such cases, you can use the eager: true option. Be cautious, as this can impact initial load performance by forcing the module to load upfront.

Both your host and remote applications should typically define the same common libraries as shared. This tells Module Federation that these dependencies are part of the shared pool.

Module Federation then orchestrates which application actually loads the dependency and makes it available to others, ensuring only one copy exists in the browser.

When react and react-dom are configured as shared, your application code can simply import them as usual. Module Federation handles the underlying logic to ensure they are loaded efficiently and only once.

This minimal React entry point demonstrates how standard imports leverage shared dependencies:

• Smaller Bundle Sizes: Prevents common libraries from being duplicated across different Micro Frontends, directly reducing the total amount of code users download.
• Improved Performance: Less code to download, parse, and execute means faster initial page load times and a more responsive user experience.
• Consistent Versions: Helps ensure all parts of your federated application use the same version of a library, reducing potential conflicts and unexpected behavior.

Module Federation's shared configuration is crucial for efficient Micro Frontends. Which option correctly describes a key benefit of using shared dependencies?

We've learned how Module Federation's shared configuration is vital for optimizing Micro Frontends. By defining common libraries as shared, you prevent them from being bundled multiple times.

This leads to smaller initial load times, better performance, and more consistent dependency versions across your federated applications.

Next, we'll dive deeper into managing Singleton Modules & Versioning to ensure robust shared dependency handling.