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react: Make value returned by useState Readonly #64099

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SpLouk wants to merge 2 commits into from
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react: Make value returned by useState Readonly #64099

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d097fd7
Make value returned by useState Readonly
Jan 26, 2023
4665ec5
use DeepReadonly
Jan 26, 2023
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3 changes: 2 additions & 1 deletion types/react/package.json
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Original file line number Diff line number Diff line change
@@ -1,7 +1,8 @@
{
"private": true,
"dependencies": {
"csstype": "^3.0.2"
"csstype": "^3.0.2",
"utility-types": "^3.10.0"
},
"exports": {
".": {
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5 changes: 3 additions & 2 deletions types/react/v17/index.d.ts
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Expand Up @@ -34,6 +34,7 @@
import * as CSS from 'csstype';
import * as PropTypes from 'prop-types';
import { Interaction as SchedulerInteraction } from 'scheduler/tracing';
import { DeepReadonly } from "utility-types";

type NativeAnimationEvent = AnimationEvent;
type NativeClipboardEvent = ClipboardEvent;
Expand Down Expand Up @@ -918,15 +919,15 @@ declare namespace React {
* @version 16.8.0
* @see https://reactjs.org/docs/hooks-reference.html#usestate
*/
function useState<S>(initialState: S | (() => S)): [S, Dispatch<SetStateAction<S>>];
function useState<S>(initialState: S | (() => S)): [DeepReadonly<S>, Dispatch<SetStateAction<S>>];
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@eps1lon eps1lon Jan 26, 2023

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Would a Readonly here suffice for the majority of use cases? I'm mainly concerned about perf here.

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@SpLouk SpLouk Jan 26, 2023

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I think DeepReadonly would be preferred to prevent mutating nested members of an object.

// convenience overload when first argument is omitted
/**
* Returns a stateful value, and a function to update it.
*
* @version 16.8.0
* @see https://reactjs.org/docs/hooks-reference.html#usestate
*/
function useState<S = undefined>(): [S | undefined, Dispatch<SetStateAction<S | undefined>>];
function useState<S = undefined>(): [DeepReadonly<S> | undefined, Dispatch<SetStateAction<S | undefined>>];
/**
* An alternative to `useState`.
*
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