Integrating JavaScript Module Federation with legacy applications in Webpack 5

18 Sep 2023

TechBlog

With the introduction of Webpack 5, JavaScript Module Federation has become a powerful feature to integrate legacy applications. It allows you to share and consume modules across different applications in a more efficient and flexible way.

What is JavaScript Module Federation?

JavaScript Module Federation is a feature introduced in Webpack 5 that enables you to dynamically load and share JavaScript modules across different applications. It solves the problem of creating standalone applications that can maintain their own codebase while sharing modules with other applications.

Why use JavaScript Module Federation?

Integrating legacy applications with JavaScript Module Federation has several benefits:

Code sharing: You can share modules across multiple applications without duplicating code or dependencies, reducing both development and maintenance efforts.
Version independence: Each application can maintain its own version of a shared module, allowing for independent updates and avoiding version conflicts.
Isolation: Each application can encapsulate its own state and logic, providing better isolation and reducing the risk of side effects.

Integrating JavaScript Module Federation with legacy applications

To integrate JavaScript Module Federation with legacy applications in Webpack 5, follow these steps:

Setup Module Federation in your Webpack configuration file of the legacy application using the ModuleFederationPlugin. Configure the name, filename, remotes, and exposes options to specify the modules you want to share and consume.

// webpack.config.js
const { ModuleFederationPlugin } = require('webpack').container;

module.exports = {
  // ...
  plugins: [
    new ModuleFederationPlugin({
      name: 'legacyApp',
      filename: 'remoteEntry.js',
      remotes: {
        sharedApp: 'sharedApp@https://example.com/sharedApp/remoteEntry.js',
      },
      exposes: {
        './sharedComponent': './src/sharedComponent',
      },
    }),
  ],
};

Build and deploy the legacy application using the updated Webpack configuration. This will generate the remoteEntry.js file, which contains the code necessary to consume modules from remote applications.

Import and use remote modules in your legacy application. You can use the syntax import('sharedApp/sharedComponent') to dynamically load and use modules from the shared application.

// index.js
import('sharedApp/sharedComponent').then((module) => {
  const sharedComponent = module.default;
  // Use the shared component in your legacy application
});

Deploy and load the shared application and the legacy application together. The legacy application will fetch the remoteEntry.js file from the shared application’s URL and dynamically load the shared modules.
```

<script src="https://example.com/sharedApp/remoteEntry.js"></script>
<script src="legacyApp.js"></script>
```

Conclusion

JavaScript Module Federation in Webpack 5 provides a powerful mechanism to integrate legacy applications. By leveraging code sharing, version independence, and isolation, you can enhance your development process and improve application architecture.

#TechBlog #JavaScript #Webpack5