# Universal Async Component Async component that works in server and client. It will allows code splitting that works for universal apps. ## What is this? This is solving the [hard problem](https://github.com/ReactTraining/react-router/blob/d64ed0150b41df02b083f090b6682261c819a91e/packages/react-router-dom/docs/guides/code-splitting.md#code-splitting--server-rendering) of mixing code splitting and server side rendering. To avoid "flash of contents" in the initial page load server must include dynamic chunks required to render that screen in the HTML response. Using this library and adding corresponding components to your build system you can achieve that. ## Example project See the [**example repo**](https://github.com/mohsen1/universal-async-component-example) ## Usage ```js import { getComponentAsync } from 'universal-async-component'; const AsyncHelloWorld = getComponentAsync({ loader: () => import('./hello') }); const App = () => ``` ## Server side rendering To make server-side rendering work you should update your server code to collect additional required chunks and also update your Webpack config to replace `import()` calls with something special that makes all of this work. ### 1. Add `CaptureChunks` Wrap you app with `CaptureChunks` in your server renderer. You need to provide Webpack client side stats to it. Also, pass an empty array ```jsx const additionalChunks = []; var htmlString = ReactDOM.renderToString( ); ``` After above code is run, `additionalChunks` is populated with all chunkIds that is required to render current `App`. Use Webpack [`StatsPlugin`](https://www.npmjs.com/package/webpack-stats-plugin) you can write the stats to disk: ```js new StatsPlugin({ filename: 'client-stats.json', fields: ['chunks', 'publicPath', 'assets'], }) ``` ### 2. Use `additionalChunks` Use `additionalChunks` retrieved from `CaptureChunks` to append required chunks ```js res.send(`

${htmlString}

${additionalChunks.map(chunkId => ``)} `) ``` Note that additional chunks must come before the main bundle and after Webpack bootstrap script. It's easy to extract out Webpack bootstrap by using `CommonsChunkPlugin` plugin: ```js new webpack.optimize.CommonsChunkPlugin({ names: ['bootstrap'], filename: 'webpack-bootstrap.js', minChunks: Infinity }), ``` ### 3. Add `"string-replace-loader"` Add `"string-replace-loader"` before any of other loaders in your **client and server** Webpack config and require options from `"universal-async-component"`: ```js const { stringReplaceLoaderOptions } = require('universal-async-component'); const config = { rules: [ test: /\.jsx?/, use: { loader: "string-replace-loader", options: stringReplaceLoaderOptions, }, ], } ``` Note: this will go away once React can render async components