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feat:
useComponentWillReceiveUpdate
(#24)
Co-authored-by: Sukka <isukkaw@gmail.com>
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--- | ||
title: useComponentWillReceiveUpdate | ||
--- | ||
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# useComponentWillReceiveUpdate | ||
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import ExportMetaInfo from '../components/export-meta-info'; | ||
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<ExportMetaInfo /> | ||
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Change states based on changed props during a re-render. The name of the hook comes from [`UNSAFE_componentWillReceiveProps` method of class components](https://react.dev/reference/react/Component#unsafe_componentwillreceiveprops). | ||
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## Usage | ||
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```js | ||
import { useComponentWillReceiveUpdate } from 'foxact/use-abortable-effect'; | ||
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function Component(props) { | ||
const [a, setA] = useState('') | ||
const [b, setB] = useState('') | ||
// when props.x changed, only reset a, not b | ||
useComponentWillReceiveUpdate(() => { | ||
setA('') | ||
}, [props.x]); | ||
} | ||
``` | ||
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If you're using useEffect like this: | ||
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```js | ||
const [state, setState] = useState(false) | ||
useEffect(() => setState(false), [props.someProp]) | ||
``` | ||
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Don't do it. See [Adjusting some state when a prop changes](https://react.dev/learn/you-might-not-need-an-effect#adjusting-some-state-when-a-prop-changes) or [Storing information from previous renders](https://react.dev/reference/react/useState#storing-information-from-previous-renders) | ||
It should be like this: | ||
```js | ||
const [prev, setPrev] = useState(state) | ||
if (prev !== state) { | ||
setPrev(state) | ||
setState(false) | ||
} | ||
``` | ||
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This hook is a helper for the above pattern. | ||
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```js | ||
useComponentWillReceiveUpdate(() => setState(false), [state]) | ||
``` | ||
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This should only apply to states of the current component. Modifying states of other components causes React reporting errors. You may also want to read [(Avoid) Notifying parent components about state changes](https://react.dev/learn/you-might-not-need-an-effect#notifying-parent-components-about-state-changes) and [(Avoid) Passing data to the parent](https://react.dev/learn/you-might-not-need-an-effect#passing-data-to-the-parent). | ||
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If you really need to directly modify other components' states (E.g. when working with third-party libraries/components/SDKs where you don't have control of that code), use `flushSync` to separate two state updates: | ||
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```js | ||
import { flushSync } from 'react-dom' | ||
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useComponentWillReceiveUpdate(() => { | ||
// Force React to immediately flush scheduled/batched updates | ||
flushSync(() => setLocalState(false)) | ||
// By the time flushSync finishes and reaches this line, the DOM update | ||
// for local state change has finished, you can now safely trigger parent | ||
// components' re-render. | ||
props.setParentState(false) | ||
}, [state]) | ||
``` |
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import { useState } from 'react'; | ||
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/** | ||
* @see {https://foxact.skk.moe/use-component-will-receive-update} | ||
*/ | ||
export function useComponentWillReceiveUpdate(callback: () => void, deps: readonly unknown[]) { | ||
deps = [...deps]; | ||
const [prev, setPrev] = useState(deps); | ||
let changed = deps.length !== prev.length; | ||
for (let i = 0; i < deps.length; i += 1) { | ||
if (changed) break; | ||
if (prev[i] !== deps[i]) changed = true; | ||
} | ||
if (changed) { | ||
setPrev(deps); | ||
callback(); | ||
} | ||
} |