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17 changes: 16 additions & 1 deletion src/content/learn/react-compiler/introduction.md
Original file line number Diff line number Diff line change
Expand Up @@ -50,6 +50,21 @@ const ExpensiveComponent = memo(function ExpensiveComponent({ data, onClick }) {
});
```


<Note>

This manual memoization has a subtle bug that breaks memoization:

```js [[2, 1, "() => handleClick(item)"]]
<Item key={item.id} onClick={() => handleClick(item)} />
```

Even though `handleClick` is wrapped in `useCallback`, the arrow function `() => handleClick(item)` creates a new function every time the component renders. This means that `Item` will always receive a new `onClick` prop, breaking memoization.

The React Compiler is able to optimize this correctly with or without the arrow function, ensuring that `Item` only re-renders when `props.onClick` changes.
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nit: drop the "the", just React Compiler


</Note>

### After React Compiler {/*after-react-compiler*/}

With React Compiler, you write the same code without manual memoization:
Expand All @@ -74,7 +89,7 @@ function ExpensiveComponent({ data, onClick }) {

_[See this example in the React Compiler Playground](https://playground.react.dev/#N4Igzg9grgTgxgUxALhAMygOzgFwJYSYAEAogB4AOCmYeAbggMIQC2Fh1OAFMEQCYBDHAIA0RQowA2eOAGsiAXwCURYAB1iROITA4iFGBERgwCPgBEhAogF4iCStVoMACoeO1MAcy6DhSgG4NDSItHT0ACwFMPkkmaTlbIi48HAQWFRsAPlUQ0PFMKRlZFLSWADo8PkC8hSDMPJgEHFhiLjzQgB4+eiyO-OADIwQTM0thcpYBClL02xz2zXz8zoBJMqJZBABPG2BU9Mq+BQKiuT2uTJyomLizkoOMk4B6PqX8pSUFfs7nnro3qEapgFCAFEA)_

React Compiler automatically applies the equivalent optimizations, ensuring your app only re-renders when necessary.
React Compiler automatically applies the optimal memoization, ensuring your app only re-renders when necessary.

<DeepDive>
#### What kind of memoization does React Compiler add? {/*what-kind-of-memoization-does-react-compiler-add*/}
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