@arthurgeron/eslint-plugin-react-usememo - npm Package Compare versions

Comparing version 0.0.3 to 0.0.4

package.json

		{
		"name": "@arthurgeron/eslint-plugin-react-usememo",
		"version": "0.0.3",
		"version": "0.0.4",
		"description": "",
		@@ -9,3 +9,3 @@ "main": "dist/index.js",
		"type": "git",
		"url": "https://github.com/steadicat/eslint-plugin-react-memo.git"
		"url": "https://github.com/arthurgeron/eslint-plugin-react-usememo.git"
		},
		@@ -12,0 +12,0 @@ "license": "MIT",

121

README.md

		# eslint-plugin-react-usememo

		Enforce that all function components are wrapped in `React.memo`, and that all props and deps are wrapped in `useMemo`/`useCallback` so they don’t break memo.
		Enforce that all function components are wrapped in `React.memo`, and that all props and deps are wrapped in `useMemo`/`useCallback` so they don’t break memo or cause unecessary expensive re-renders in children (e.g. React Native's FlatLists, useEffect, useMemo).

		Rationale: [Why we memo all the things](https://attardi.org/why-we-memo-all-the-things/).
		## Rationale
		[Why we memo all the things](https://attardi.org/why-we-memo-all-the-things/).
		React Native's own [docs](https://reactnative.dev/docs/0.61/optimizing-flatlist-configuration#avoid-anonymous-function-on-renderitem) state how it's important to use static or memoized as props for complex children (FlatList on that case), that applies even more broadly when we are talking about custom components (the Components you've created), it might not seem necessary at first but you'll be making a bet that the component in question will never grow to use `memo` or those props in hooks (i.e. useEffect, useMemo, useCallback), you'll only notice once your solution starts freezing and dropping frames, that's why using the `require-usememo` rule is recommended.


		## Installation
		# Installation

		@@ -19,7 +21,7 @@ ```

		## Usage
		# Usage

		To enable the plugin add the following to the `plugin` property your `eslintrc` file:
		```json
		plugins: ["@arthurgeron/react-usememo"],
		"plugins": ["@arthurgeron/react-usememo"],
		```
		@@ -29,15 +31,10 @@
		```json
		rules: {
		"rules": {
		"@arthurgeron/react-usememo/require-usememo": [2],
		},
		```
		## Rules
		# Rules

		### `require-memo`
		## `require-usememo` Recommended

		Requires all function components to be wrapped in `React.memo()`.
		May be useful when used with overrides in your eslint config, I do not recommend enabling this globally.

		### `require-usememo` Recommended

		Requires complex values (objects, arrays, functions, and JSX) that get passed props or referenced as a hook dependency to be wrapped in `React.useMemo()` or `React.useCallback()`.
		@@ -49,4 +46,77 @@

		### `require-usememo-children` Advanced
		## Incorrect
		```JavaScript
		function Component() {

		const [data, setData] = useState([]);


		// This will be redeclared each render
		function renderItem({ item }) {
		return <Text>item.name</Text>;
		}

		// Data isn't redeclared each ender but `[]` is
		<FlatList renderItem={renderItem} data={data ?? []} />
		}
		```
		In the previous example there are two issues, a function and a object that will be dynamically redeclared each time the component renders, which will cause FlatList to keep re-rendering even when the input data hasn't changed.

		## Correct
		```JavaScript
		// Has no dynamic dependencies therefore should be static, will be declared only once.
		function renderItem({ item }) {
		return <Text>item.name</Text>;
		}

		const EMPTY_ARRAY = [];

		function Component() {

		const [data, setData] = useState(EMPTY_ARRAY);



		<FlatList renderItem={renderItem} data={data ?? EMPTY_ARRAY} />
		}
		```
		## Correct
		```JavaScript
		const EMPTY_ARRAY = [];

		function Component() {
		const [data, setData] = useState(EMPTY_ARRAY);
		const [isEditing, setIsEditing] = useState(false);

		// Has dynamic dependencies but will only be re-declared when isEditing or the input data changes
		const renderItem = useCallback(({ item }) => {
		return <Text>{isEditing ? 'item.name' : 'Editing'}</Text>;
		}, [isEditing]);

		<FlatList renderItem={renderItem} data={data ?? EMPTY_ARRAY} />
		}
		```
		## `require-memo`

		Requires all function components to be wrapped in `React.memo()`.
		May be useful when used with overrides in your eslint config, I do not recommend enabling this globally, while there's great advantaje in memoing a complex tree of components some smaller/basic components with no children might not need to be memoized.

		## Incorrect
		```JavaScript
		export default function Component() {

		<Text>This is a component</Text>
		}
		```

		## Correct
		```JavaScript
		export default memo(function Component() {

		<Text>This is a component</Text>
		});
		```

		## `require-usememo-children` Advanced

		Requires complex values (objects, arrays, functions, and JSX) that get passed as children to be wrapped in `React.useMemo()` or `React.useCallback()`.
		@@ -57,1 +127,24 @@
		- `{strict: true}`: Fails even in cases where it is difficult to determine if the value in question is a primitive (string or number) or a complex value (object, array, etc.).

		## Incorrect
		```JavaScript
		function Component() {

		<View>
		<>
		<OtherComponent />
		</>
		</View>
		}
		```

		## Correct
		```JavaScript
		function Component() {

		const children = useMemo(() => (<OtherComponent />), []);
		<View>
		{children}
		</View>
		}
		```

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