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

In React 18, useState update calls are batched for improved performance. A new API — `ReactDOM.flushSync` — lets us selectively escape batching. This option is useful when reading the DOM after state changes. Use `ReactDOM.flushSync` to exempt specific state updates from batching.

https://app.egghead.io/api/v1/lessons/react-opt-out-of-automatic-batching-with-reactdom-flushsync/subtitles

Instructor: [0:00] ReactDOM 18 provides a way to opt out of automatic batching of state updates. Because of automatic batching, these two state updates always happen in the same rerender. We can split them using ReactDOM flushSync, simply wrap the update in ReactDOM.flushSync.

[0:26] With this, we're separating these updates by forcing this one to flush to the DOM first. Now, every time we click our button, we see two individual updates. We can repeat this process for as many state updates as we like.

Opt-out of Automatic Batching with ReactDOM.flushSync

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Migrate a Client-Side Application to React 18 Beta