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      • Async Startup in Module Federation

      Sep 5, 2024

      We're excited to announce a new experimental feature: experiments.asyncStartup = true.

      This release introduces asynchronous startup, enabling automatic async initialization for Module Federation entrypoints.

      🚀 Key Features

      Automatic Async Initialization

      With async startup enabled, dynamic imports (import()) at the top of your app are no longer required. All entrypoints will now initialize asynchronously by default. This means:

      • No more eager errors
      • No need for "async boundaries" in userland code
      • Automatic handling of async initialization
      Note

      This only affects entry point initialization. You can still use dynamic imports normally throughout your application, including for importing remote modules. This feature doesn't change or limit how dynamic imports work in your code.

      Tip

      Note: Asynchronous entrypoints will always export a promise. This is particularly relevant if you're manually requiring a bundled entrypoint or exposing something like a UMD library to the global scope.

      Before & After Comparison

      See how the new async behavior simplifies entrypoints. Click on the "Before" and "After" tabs to see the difference.

      Before
      After
      // entrypoint
import('./bootstrap.js')

// bootstrap.js
import React from 'react';
import ReactDOM from 'react-dom/client';
import App from './App';

const root = ReactDOM.createRoot(document.getElementById('root')!);
root.render(
<React.StrictMode>
  <App />
</React.StrictMode>,
);

      Important Notes

      When using async startup:

      • All entrypoints initialize asynchronously by default
      • Exports from entrypoints will be promises that resolve to the actual exports
      • No manual async boundaries or dynamic imports needed
      • Eager consumption errors are automatically prevented through async initialization

      This feature simplifies Module Federation setup by removing the need for manual async handling while ensuring proper initialization of federated modules.