Name: Use React 18's New Root API Alongside the Legacy Root API
Uploaded: 2021-10-29T18:44:50-05:00
Description: Utilize both React root APIs to migrate your app. We can render a portion of our app using the legacy root API (v17 compatible) and a second using the new root API (v18 exclusive). This option makes it possible to migrate portions of your app at a time.

Gradual Adoption Strategy of React 18

Update React Dependencies with the @next Version Tag

Replace Legacy Root API with New Root API

Use React 18's New Root API Alongside the Legacy Root API

Replace Legacy Root API's Callback Argument

Conditionally Render with Legacy Root API or New Root API

Opt-in to Automatic Batching with createRoot

Remove unstable_batchedUpdates Calls

Opt-out of Automatic Batching with ReactDOM.flushSync

Handle Class Component setState edge-case with ReactDOM.flushSync

Stay up-to-date on React 18 progress with the React Working Group

Migrate a Client-Side Application to React 18 Beta

Utilize both React root APIs to migrate your app. We can render a portion of our app using the legacy root API (v17 compatible) and a second using the new root API (v18 exclusive). This option makes it possible to migrate portions of your app at a time.

https://app.egghead.io/api/v1/lessons/react-use-react-18-s-new-root-api-alongside-the-legacy-root-api/subtitles

Instructor: [0:00] One of the nice outcomes of ReactDOM shipping with two root APIs is that we can render to different parts of our page using the different root APIs. If part of our app isn't quite stable yet, with the new root API, we can migrate those selectively. Let's render to both of these roots.

[0:19] For Root 1, we'll use the new React root API, ReactDOM.createRoot from root1.render(<App />). Hit refresh in our browser. This takes a root API, so we can pass that along to keep track of these differences. To Root 2, we'll use the legacy ReactDOM.render() API, providing the component as the first argument.

[0:50] Let's save, re-render our page, update this to Root 17, not that it is 17 but that it behaves like 17. There we go.

[1:03] Because we added this one second, we can confirm through this warning message that, indeed, it is using the ReactDOM 17 legacy root API, rendering everything in that root as if it were version 17.

Use React 18's New Root API Alongside the Legacy Root API

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Migrate a Client-Side Application to React 18 Beta