Oxlint

https://oxc.rs/docs/guide/usage
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Oxlint is a high-performance linter for JavaScript and TypeScript, built on the Oxc compiler stack,...
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### Quick start: migrate from Prettier with npm, pnpm, yarn, or bun

Source: https://oxc.rs/docs/guide/usage/formatter/migrate-from-prettier.html

Quick start migration commands for npm, pnpm, yarn, and bun. Each installs oxfmt, runs the Prettier migration, and formats the project.

```bash
$ npm add -D oxfmt@latest && npx oxfmt --migrate=prettier && npx oxfmt

```

```bash
$ pnpm add -D oxfmt@latest && pnpm oxfmt --migrate=prettier && pnpm oxfmt

```

```bash
$ yarn add -D oxfmt@latest && yarn oxfmt --migrate=prettier && yarn oxfmt

```

```bash
$ bun add -D oxfmt@latest && bunx oxfmt --migrate=prettier && bunx oxfmt

```

--------------------------------

### Install migrate-oxlint skill

Source: https://oxc.rs/docs/guide/usage/linter/migrate-from-eslint.html

Install the `migrate-oxlint` skill into your coding agent using npx. After installation, run `/migrate-oxlint` to perform the migration.

```bash
npx skills add https://github.com/oxc-project/oxc --skill migrate-oxlint
```

--------------------------------

### Install migrate-oxfmt skill with npx

Source: https://oxc.rs/docs/guide/usage/formatter/migrate-from-prettier.html

Installs the migrate-oxfmt skill into your coding agent. After installation, run /migrate-oxfmt to perform an interactive, agent-guided migration.

```bash
npx skills add https://github.com/oxc-project/oxc --skill migrate-oxfmt

```

--------------------------------

### Install Oxlint with pnpm

Source: https://oxc.rs/docs/guide/usage/linter.html

Install Oxlint as a dev dependency using pnpm. This is the recommended setup before adding lint scripts to package.json.

```sh
pnpm add -D oxlint
```

--------------------------------

### Correct code examples

Source: https://oxc.rs/docs/guide/usage/linter/rules/eslint/no-useless-computed-key

Examples of correct code that do not use unnecessary computed keys.

```js
const a = { a: 0 };
const b = { 0: 0 };
const c = { x() {} };
const e = { "0+1,234": 0 };

class Foo {
  foo = "bar";
  0() {}
  a() {}
  static foo = "bar";
}
```

--------------------------------

### Example module ./foo.js

Source: https://oxc.rs/docs/guide/usage/linter/rules/import/namespace

Defines a module that exports a constant 'bar'. This is used as the imported namespace in the examples.

```javascript
// ./foo.js
export const bar = "I'm bar";
```

--------------------------------

### Unix output example

Source: https://oxc.rs/docs/guide/usage/linter/output-formats.html

Example of oxlint's --format=unix output, a basic single-line format.

```text
test.js:5:1: `debugger` statement is not allowed [Error/eslint(no-debugger)]

1 problem
```

--------------------------------

### Example config with 'avoid' option

Source: https://oxc.rs/docs/guide/usage/linter/rules/unicorn/switch-case-braces

Example configuration using the 'avoid' option, which allows braces only when needed for scoping.

```json
"unicorn/switch-case-braces": ["error", "avoid"]
```

--------------------------------

### Configuration examples for react/forbid-component-props

Source: https://oxc.rs/docs/guide/usage/linter/rules/react/forbid-component-props

Configuration examples for the forbid option, showing string and object forms with message, allowedFor, and disallowedFor.

```json
["error", { "forbid": ["className", "style"] }]
```

```json
["error", { "forbid": [{ "propName": "className", "message": "Use variant instead" }] }]
```

```json
["error", { "forbid": [{ "propName": "className", "allowedFor": ["ReactModal"] }] }]
```

```json
["error", { "forbid": [{ "propNamePattern": "**-**", "disallowedFor": ["Foo"] }] }]
```

--------------------------------

### allowedPrefixes option example

Source: https://oxc.rs/docs/guide/usage/linter/rules/jest/prefer-lowercase-title

Correct code for the allowedPrefixes option: allows titles to start with the specified prefix (e.g., "GET").

```javascript
/* jest/prefer-lowercase-title: ["error", { "allowedPrefixes": ["GET"] }] */
describe("GET /live");
```

--------------------------------

### Install oxlint globally for Neovim

Source: https://oxc.rs/docs/guide/usage/linter/editors.html

Installs oxlint globally, required for the Neovim LSP setup.

```sh
npm i -g oxlint
```

--------------------------------

### Example options usage

Source: https://oxc.rs/docs/guide/usage/linter/rules/import/newline-after-import

Shows how to configure the rule with options in a JSON config file.

```json
{
  "rules": {
    "import/newline-after-import": ["error", { "count": 1 }]
  }
}

```

--------------------------------

### Example project tree with nested configs

Source: https://oxc.rs/docs/guide/usage/formatter/config.html

Shows how different config files can be placed at different levels. The nearest config to each file wins.

```text
my-repo/
├── oxfmt.config.ts         # default for the whole repo
├── src/
│   └── app.ts              # uses root config
└── packages/
    └── fancy-app/
        ├── .oxfmtrc.json   # overrides for this package
        └── index.ts        # uses packages/fancy-app/.oxfmtrc.json
```

--------------------------------

### Difference: use before hook for per-file setup

Source: https://oxc.rs/docs/guide/usage/linter/writing-js-plugins.html

Shows the third difference: create is called per file, while createOnce is called once. Use the before hook for per-file setup.

```diff
-     let classCount = 0;
+     let classCount;

      return {
+       before() {
+         classCount = 0; // Reset counter
+       },
        ClassDeclaration(node) {
          classCount++;
          if (classCount === 6) {
            context.report({ message: "Too many classes", node });
          }
        },
      };
```

--------------------------------

### Neovim: Install oxfmt globally for nvim-lspconfig

Source: https://oxc.rs/docs/guide/usage/formatter/editors.html

Installs the oxfmt CLI globally via npm, required for the Neovim LSP setup.

```sh
npm i -g oxfmt
```

--------------------------------

### Difference: use createOnce instead of create

Source: https://oxc.rs/docs/guide/usage/linter/writing-js-plugins.html

Shows the second difference: use createOnce instead of create.

```diff
-   create(context) {
+   createOnce(context) {
```

--------------------------------

### Configuration: paths option

Source: https://oxc.rs/docs/guide/usage/linter/rules/eslint/no-restricted-imports

Configuration example for the `paths` option, listing module names to restrict.

```json
{"rules: {"no-restricted-imports": ["error", { "paths": ["import1", "import2"] }]}}
```

--------------------------------

### Correct code for jest/prefer-lowercase-title

Source: https://oxc.rs/docs/guide/usage/linter/rules/jest/prefer-lowercase-title

Correct example: the test description starts with a lowercase letter, satisfying the rule.

```javascript
it("adds 1 + 2 to equal 3", () => {
  expect(sum(1, 2)).toBe(3);
});
```

--------------------------------

### Configuration with allow option

Source: https://oxc.rs/docs/guide/usage/linter/rules/eslint/no-empty-function

Configuration example that allows empty constructors by setting the `allow` option.

```json
{
  "no-empty-function": [
    "error",
    {
      "allow": ["constructors"]
    }
  ]
}
```

--------------------------------

### Incorrect code for jest/prefer-lowercase-title

Source: https://oxc.rs/docs/guide/usage/linter/rules/jest/prefer-lowercase-title

Incorrect example: the test description starts with an uppercase letter, which violates the rule.

```javascript
it("Adds 1 + 2 to equal 3", () => {
  expect(sum(1, 2)).toBe(3);
});
```

--------------------------------

### ignoreTopLevelDescribe option example

Source: https://oxc.rs/docs/guide/usage/linter/rules/jest/prefer-lowercase-title

Correct code for the ignoreTopLevelDescribe option: only top-level describe blocks may start with an uppercase letter.

```javascript
/* jest/prefer-lowercase-title: ["error", { "ignoreTopLevelDescribe": true }] */
describe("MyClass", () => {
  describe("#myMethod", () => {
    it("does things", () => {
      //
    });
  });
});
```

--------------------------------

### Configuration example for amd option

Source: https://oxc.rs/docs/guide/usage/linter/rules/import/no-absolute-path

Shows configuration with `amd: true` and `commonjs: false`. AMD-style calls with absolute paths are reported, while CommonJS require calls are ignored.

```javascript
/* import/no-absolute-path: ["error", { "commonjs": false, "amd": true }] */
define(["/foo"], function (foo) {
  /*...*/
}); // reported
require(["/foo"], function (foo) {
  /*...*/
}); // reported

const foo = require("/foo"); // ignored because of explicit `commonjs: false`
```

--------------------------------

### varsIgnorePattern correct example

Source: https://oxc.rs/docs/guide/usage/linter/rules/eslint/no-unused-vars

Correct code for the `varsIgnorePattern` option when the pattern is `^_`. Variables starting with underscore are ignored, while `b` is used.

```javascript
var _a = 10;
var b = 10;
console.log(b);
```

--------------------------------

### Enable rule via CLI

Source: https://oxc.rs/docs/guide/usage/linter/rules/promise/prefer-await-to-callbacks

Command-line example to enable the rule with the promise plugin.

```bash
oxlint --deny promise/prefer-await-to-callbacks --promise-plugin
```

--------------------------------

### General JSON output example

Source: https://oxc.rs/docs/guide/usage/linter/output-formats.html

A general JSON output format. Can also be used with --rules to get a list of all Oxlint rules in JSON format.

```json
{
  "diagnostics": [
    {
      "message": "`debugger` statement is not allowed",
      "code": "eslint(no-debugger)",
      "severity": "error",
      "causes": [],
      "url": "https://oxc.rs/docs/guide/usage/linter/rules/eslint/no-debugger.html",
      "help": "Remove the debugger statement",
      "filename": "test.js",
      "labels": [
        {
          "span": {
            "offset": 38,
            "length": 9,
            "line": 5,
            "column": 1
          }
        }
      ],
      "related": []
    }
  ],
  "number_of_files": 1,
  "number_of_rules": 2,
  "threads_count": 1,
  "start_time": 0.018611917
}
```

--------------------------------

### Enable rule via CLI

Source: https://oxc.rs/docs/guide/usage/linter/rules/unicorn/no-null

Command-line example to enable the unicorn/no-null rule using the --deny flag.

```bash
oxlint --deny unicorn/no-null
```

--------------------------------

### Configure ignore option for unicorn/filename-case

Source: https://oxc.rs/docs/guide/usage/linter/rules/unicorn/filename-case

Sets an array of regular expression patterns for filenames to ignore. This example ignores filenames starting with "foo".

```json
{
  "unicorn/filename-case": [
    "error",
    {
      "ignore": ["^foo.*$"]
    }
  ]
}
```

--------------------------------

### LSP initialize request with initializationOptions

Source: https://oxc.rs/docs/guide/usage/linter/lsp-config-reference.html

Example of an `initialize` request that sends LSP options for a workspace folder. The `initializationOptions` array contains an object with `workspaceUri` and `options` fields.

```json
{
  "processId": 123,
  "rootUri": null,
  "workspaceFolders": [],
  "capabilities": {},
  "initializationOptions": [
    {
      "workspaceUri": "file:///home/user/project",
      "options": {
        "unusedDisableDirectives": "deny",
        "typeAware": true
      }
    }
  ]
}
```

--------------------------------

### Incorrect: function foo(arg) { return Boolean(arg); }

Source: https://oxc.rs/docs/guide/usage/linter/rules/eslint/new-cap

Example of incorrect code for the rule. The function 'foo' is used as a constructor but does not start with a capital letter.

```javascript
function foo(arg) {
  return Boolean(arg);
}
```

--------------------------------

### Enable unicorn/prefer-array-flat-map via config file or CLI

Source: https://oxc.rs/docs/guide/usage/linter/rules/unicorn/prefer-array-flat-map

Configuration examples to enable the rule using .oxlintrc.json, oxlint.config.ts, or the CLI.

```json
{
  "rules": {
    "unicorn/prefer-array-flat-map": "error"
  }
}
```

```ts
import { defineConfig } from "oxlint";

export default defineConfig({
  rules: {
    "unicorn/prefer-array-flat-map": "error",
  },
});
```

```bash
oxlint --deny unicorn/prefer-array-flat-map
```

--------------------------------

### Configure plugin settings with `settings`

Source: https://oxc.rs/docs/guide/usage/linter/config.html

Use `settings` for plugin-wide configuration shared by multiple rules. This example shows a monorepo + React + jsx-a11y setup with `next.rootDir`, `react.linkComponents`, and `jsx-a11y.components`.

```json
{
  "settings": {
    "next": {
      "rootDir": "apps/dashboard/"
    },
    "react": {
      "linkComponents": [{ "name": "Link", "linkAttribute": "to" }]
    },
    "jsx-a11y": {
      "components": {
        "Link": "a",
        "Button": "button"
      }
    }
  }
}
```

```ts
import { defineConfig } from "oxlint";

export default defineConfig({
  settings: {
    next: {
      rootDir: "apps/dashboard/",
    },
    react: {
      linkComponents: [{ name: "Link", linkAttribute: "to" }],
    },
    "jsx-a11y": {
      components: {
        Link: "a",
        Button: "button",
      },
    },
  },
});
```

--------------------------------

### Correct with default newIsCap: var friend = new Person();

Source: https://oxc.rs/docs/guide/usage/linter/rules/eslint/new-cap

Example of correct code with the default option { "newIsCap": true }. The constructor 'Person' starts with an uppercase letter.

```javascript
/* new-cap: ["error", { "newIsCap": true }] */

var friend = new Person();
```

--------------------------------

### Enable unicorn/prefer-at via CLI

Source: https://oxc.rs/docs/guide/usage/linter/rules/unicorn/prefer-at

Command-line example to deny the rule using `oxlint --deny unicorn/prefer-at`.

```bash
oxlint --deny unicorn/prefer-at
```

--------------------------------

### Example configuration for jest/no-restricted-matchers

Source: https://oxc.rs/docs/guide/usage/linter/rules/jest/no-restricted-matchers

Configuration object that bans specific matchers and modifiers. The value can be a custom message or null to use the default message. Bans are checked against the start of the expect chain, so to ban a matcher entirely you must specify all six permutations.

```json
{
  "jest/no-restricted-matchers": [
    "error",
    {
      "toBeFalsy": null,
      "resolves": "Use `expect(await promise)` instead.",
      "toHaveBeenCalledWith": null,
      "not.toHaveBeenCalledWith": null,
      "resolves.toHaveBeenCalledWith": null,
      "rejects.toHaveBeenCalledWith": null,
      "resolves.not.toHaveBeenCalledWith": null,
      "rejects.not.toHaveBeenCalledWith": null
    }
  ]
}
```

--------------------------------

### Initialize .oxlintrc.json with oxlint --init

Source: https://oxc.rs/docs/guide/usage/linter/quickstart.html

Initialize the .oxlintrc.json config with default values. Then customize it as needed.

```sh
oxlint --init
```

--------------------------------

### Correct: Use imported config

Source: https://oxc.rs/docs/guide/usage/linter/rules/node/no-process-env

Correct example that imports configuration and uses config.env instead of process.env.

```js
import config from "./config";

if (config.env === "development") {
  //...
}
```

--------------------------------

### Enable react/preserve-manual-memoization via CLI

Source: https://oxc.rs/docs/guide/usage/linter/rules/react/preserve-manual-memoization

Command-line example to enable the rule using --deny and --react-plugin.

```bash
oxlint --deny react/preserve-manual-memoization --react-plugin

```

--------------------------------

### Enable unicorn/prefer-at in .oxlintrc.json

Source: https://oxc.rs/docs/guide/usage/linter/rules/unicorn/prefer-at

Configuration file example to enable the rule with severity 'error'.

```json
{
  "rules": {
    "unicorn/prefer-at": "error"
  }
}
```

--------------------------------

### Incorrect code examples for jest/no-restricted-matchers

Source: https://oxc.rs/docs/guide/usage/linter/rules/jest/no-restricted-matchers

Examples of incorrect code that violate the rule with the above configuration. Each example shows a banned matcher or modifier usage.

```javascript
it("is false", () => {
  // if this has a modifier (i.e. `not.toBeFalsy`), it would be considered fine
  expect(a).toBeFalsy();
});

it("resolves", async () => {
  // all uses of this modifier are disallowed, regardless of matcher
  await expect(myPromise()).resolves.toBe(true);
});

describe("when an error happens", () => {
  it("does not upload the file", async () => {
    // all uses of this matcher are disallowed
    expect(uploadFileMock).not.toHaveBeenCalledWith("file.name");
  });
});
```

--------------------------------

### Incorrect Code Examples

Source: https://oxc.rs/docs/guide/usage/linter/rules/eslint/prefer-spread

Examples of incorrect code for the prefer-spread rule.

```javascript
foo.apply(undefined, args);
foo.apply(null, args);
obj.foo.apply(obj, args);
```

--------------------------------

### Enable react/display-name via CLI

Source: https://oxc.rs/docs/guide/usage/linter/rules/react/display-name

Command-line example to enable the rule using the --deny flag and --react-plugin.

```bash
oxlint --deny react/display-name --react-plugin
```

--------------------------------

### Initialize oxfmt config file

Source: https://oxc.rs/docs/guide/usage/formatter/quickstart.html

Creates a .oxfmtrc.json file with default settings.

```sh
oxfmt --init
```

--------------------------------

### Install @oxc-node/cli with npm, pnpm, yarn, or bun

Source: https://oxc.rs/docs/guide/usage/oxc-node.html

Install the @oxc-node/cli package as a development dependency using your preferred package manager. A project-local installation keeps the runner version consistent across your team; you can also install globally to invoke oxnode outside a project or package script.

```sh
$ npm add -D @oxc-node/cli
```

```sh
$ pnpm add -D @oxc-node/cli
```

```sh
$ yarn add -D @oxc-node/cli
```

```sh
$ bun add -D @oxc-node/cli
```

--------------------------------

### Enable jsdoc/require-param via CLI

Source: https://oxc.rs/docs/guide/usage/linter/rules/jsdoc/require-param

Command-line example to enable the rule with the jsdoc plugin.

```bash
oxlint --deny jsdoc/require-param --jsdoc-plugin
```

--------------------------------

### Neovim: Install coc-oxc with coc.nvim

Source: https://oxc.rs/docs/guide/usage/formatter/editors.html

Installs the coc-oxc extension for coc.nvim to integrate Oxfmt.

```vim
:CocInstall coc-oxc
```

--------------------------------

### Enable jest/prefer-snapshot-hint via CLI

Source: https://oxc.rs/docs/guide/usage/linter/rules/jest/prefer-snapshot-hint

Command line example for enabling the rule with the --deny flag and the jest plugin.

```bash
oxlint --deny jest/prefer-snapshot-hint --jest-plugin
```

--------------------------------

### Generator function example

Source: https://oxc.rs/docs/guide/usage/linter/rules/eslint/func-names

Example of a generator function expression using the function* syntax.

```js
function* foobar(i) {
  yield i;
  yield i + 10;
}
```

--------------------------------

### Enable rule via CLI

Source: https://oxc.rs/docs/guide/usage/linter/rules/vitest/no-conditional-in-test

Command-line example to enable the rule with --deny and the vitest plugin.

```bash
oxlint --deny vitest/no-conditional-in-test --vitest-plugin
```

--------------------------------

### Correct code examples for jsx-a11y/img-redundant-alt

Source: https://oxc.rs/docs/guide/usage/linter/rules/jsx_a11y/img-redundant-alt

These examples show img elements with alt text that avoids redundant words. The second example passes because the element is hidden, and the third passes because 'photo' is a variable name.

```jsx
<img src="foo" alt="Foo eating a sandwich." />
<img src="bar" aria-hidden alt="Picture of me taking a photo of an image" /> // Will pass because it is hidden.
<img src="baz" alt={`Baz taking a ${photo}`} /> // This is valid since photo is a variable name.
```

--------------------------------

### Correct: Using describe.each

Source: https://oxc.rs/docs/guide/usage/linter/rules/jest/prefer-each

Shows the recommended approach using `describe.each` to run parameterized tests, which is clearer and more concise.

```javascript
describe.each(items)("item", (item) => {
  expect(item).toBe("foo");
});
```

--------------------------------

### Correct code examples for typescript/prefer-optional-chain

Source: https://oxc.rs/docs/guide/usage/linter/rules/typescript/prefer-optional-chain

Examples of correct code that use optional chaining expressions.

```ts
foo?.bar;
foo?.bar?.baz;
foo?.["bar"];
foo?.bar?.baz?.buzz;
foo?.bar?.baz.buzz;
foo?.bar.baz?.buzz;
foo?.bar;
```

--------------------------------

### Per-extension configuration examples

Source: https://oxc.rs/docs/guide/usage/linter/rules/import/extensions

Shows per-extension configuration examples. The first configuration enforces extensions for .vue and disallows for .ts, while .css is ignored. The second configuration with ignorePackages ignores package imports.

```javascript
// Configuration: { "vue": "always", "ts": "never" }
import Component from "./Component.vue"; // ✓ OK - .vue configured as "always"
import utils from "./utils"; // ✓ OK - .ts configured as "never"
import styles from "./styles.css"; // ✓ OK - .css not configured, ignored

// Configuration: ["ignorePackages", { "js": "never", "ts": "never" }]
import foo from "./foo"; // ✓ OK - no extension
import bar from "lodash/fp"; // ✓ OK - package import, ignored (ignorePackages sets this to true)
```

--------------------------------

### Correct code examples for prefer-await-to-callbacks

Source: https://oxc.rs/docs/guide/usage/linter/rules/promise/prefer-await-to-callbacks

These examples show patterns that comply with the rule: using await, async functions, generators, and event listeners.

```javascript
await doSomething(arg);
async function doSomethingElse() {}
function* generator() {
  yield yieldValue((err) => {});
}
eventEmitter.on("error", (err) => {});
```

--------------------------------

### Incorrect TypeScript examples for no-unused-vars

Source: https://oxc.rs/docs/guide/usage/linter/rules/eslint/no-unused-vars

Incorrect TypeScript examples: a self-referential type and an unused enum.

```ts
type A = Array<A>;

enum Color {
  Red,
  Green,
  Blue,
}
```

--------------------------------

### Incorrect with statement example

Source: https://oxc.rs/docs/guide/usage/linter/rules/eslint/no-with

Shows an example of incorrect code that uses a with statement, which the rule disallows.

```javascript
with (point) {
  r = Math.sqrt(x * x + y * y); // is r a member of point?
}
```

--------------------------------

### Configure rules in .oxlintrc.json

Source: https://oxc.rs/docs/guide/usage/linter/config-file-reference.html

Example of the `rules` configuration object in an `.oxlintrc.json` file. Shows how to set rule severities and pass options to a rule.

```json
{
  "$schema": "./node_modules/oxlint/configuration_schema.json",
  "rules": {
    "eqeqeq": "warn",
    "import/no-cycle": "error",
    "prefer-const": [
      "error",
      {
        "ignoreReadBeforeAssign": true
      }
    ]
  }
}
```

--------------------------------

### CLI command to enable import/first

Source: https://oxc.rs/docs/guide/usage/linter/rules/import/first

Command-line usage to enable the import/first rule with the import plugin.

```bash
oxlint --deny import/first --import-plugin

```

--------------------------------

### Install oxc-transform-react

Source: https://oxc.rs/docs/guide/usage/transformer/react-compiler.html

Install the dedicated React transform package required to use the React Compiler integration.

```sh
pnpm add -D oxc-transform-react
```

--------------------------------

### Enable react/no-unsafe via CLI

Source: https://oxc.rs/docs/guide/usage/linter/rules/react/no-unsafe

Command-line example to enable the rule using --deny and the react plugin.

```bash
oxlint --deny react/no-unsafe --react-plugin
```

--------------------------------

### checkTypePredicates example

Source: https://oxc.rs/docs/guide/usage/linter/rules/typescript/no-unnecessary-condition

Example for the checkTypePredicates option: narrow(value) is unnecessary because value already has type true.

```ts
declare const narrow: (value: unknown) => value is true;
const value = true;
if (narrow(value)) {
  // ...
}
```

--------------------------------

### Incorrect code example

Source: https://oxc.rs/docs/guide/usage/linter/rules/oxc/no-map-spread

Example of incorrect code for this rule: using object spread in a map callback.

```js
const arr = [{ a: 1 }, { a: 2 }, { a: 3 }];
const arr2 = arr.map((obj) => ({ ...obj, b: obj.a * 2 }));
```

--------------------------------

### Enable vars-on-top via CLI

Source: https://oxc.rs/docs/guide/usage/linter/rules/eslint/vars-on-top

Command-line example to enable the rule with --deny flag.

```bash
oxlint --deny vars-on-top
```

--------------------------------

### Install Oxfmt with npm, pnpm, yarn, bun, or deno

Source: https://oxc.rs/docs/guide/usage/formatter/migrate-from-prettier.html

Install Oxfmt as a dev dependency using npm, pnpm, yarn, bun, or deno. Run this after upgrading Prettier to v3.8 to minimize formatting differences.

```bash
$ npm add -D oxfmt@latest

```

```bash
$ pnpm add -D oxfmt@latest

```

```bash
$ yarn add -D oxfmt@latest

```

```bash
$ bun add -D oxfmt@latest

```

```bash
$ deno add -D npm:oxfmt@latest

```

--------------------------------

### Correct Code Examples

Source: https://oxc.rs/docs/guide/usage/linter/rules/eslint/prefer-spread

Examples of correct code for the prefer-spread rule, including cases where spread is not applicable.

```javascript
// Using spread syntax
foo(...args);
obj.foo(...args);

// The `this` binding is different.
foo.apply(obj, args);
obj.foo.apply(null, args);
obj.foo.apply(otherObj, args);

// The argument list is not variadic.
// Those are warned by the `no-useless-call` rule.
foo.apply(undefined, [1, 2, 3]);
foo.apply(null, [1, 2, 3]);
obj.foo.apply(obj, [1, 2, 3]);
```

--------------------------------

### restrictDefaultExports.namespaceFrom incorrect example

Source: https://oxc.rs/docs/guide/usage/linter/rules/eslint/no-restricted-exports

Incorrect code example for the `restrictDefaultExports.namespaceFrom` option, which restricts `export * as default from` declarations.

```js
export * as default from "foo";
```

--------------------------------

### Enable rule via CLI

Source: https://oxc.rs/docs/guide/usage/linter/rules/vitest/no-alias-methods

Command-line example to enable the rule with the vitest plugin.

```bash
oxlint --deny vitest/no-alias-methods --vitest-plugin
```

--------------------------------

### Enable import/max-dependencies via .oxlintrc.json

Source: https://oxc.rs/docs/guide/usage/linter/rules/import/max-dependencies

Configuration file example to enable the rule as an error in JSON format.

```json
{
  "plugins": ["import"],
  "rules": {
    "import/max-dependencies": "error"
  }
}
```

--------------------------------

### restrictDefaultExports.direct incorrect example

Source: https://oxc.rs/docs/guide/usage/linter/rules/eslint/no-restricted-exports

Incorrect code example for the `restrictDefaultExports.direct` option, which restricts `export default` declarations.

```js
const foo = 123;
export default foo;
```

--------------------------------

### restrictDefaultExports.defaultFrom incorrect example

Source: https://oxc.rs/docs/guide/usage/linter/rules/eslint/no-restricted-exports

Incorrect code example for the `restrictDefaultExports.defaultFrom` option, which restricts `export { default } from` declarations.

```js
export { default } from "foo";
```

--------------------------------

### Set up Oxlint with pre-commit

Source: https://oxc.rs/docs/guide/usage/linter/ci.html

Configure pre-commit to run Oxlint using the mirrors-oxlint repository. Replace v0.0.0 with the latest version; the verbose option is enabled.

```yaml
repos:
  - repo: https://github.com/oxc-project/mirrors-oxlint
    rev: v0.0.0
    hooks:
      - id: oxlint
        verbose: true
```

--------------------------------

### Incorrect code examples for no-underscore-dangle

Source: https://oxc.rs/docs/guide/usage/linter/rules/eslint/no-underscore-dangle

Examples of code that violate the rule by using dangling underscores in identifiers.

```javascript
let foo_;
const __proto__ = {};
foo._bar();
```

--------------------------------

### Enable import/unambiguous via CLI

Source: https://oxc.rs/docs/guide/usage/linter/rules/import/unambiguous

Command-line example to enable the rule with the --deny flag and the import plugin.

```bash
oxlint --deny import/unambiguous --import-plugin
```

--------------------------------

### Incorrect code examples for no-plusplus

Source: https://oxc.rs/docs/guide/usage/linter/rules/eslint/no-plusplus

Examples of code that violates the rule by using ++ and -- operators.

```javascript
var x = 0;
x++;
var y = 0;
y--;
for (let i = 0; i < l; i++) {
  doSomething(i);
}
```

--------------------------------

### Enable rule via .oxlintrc.json

Source: https://oxc.rs/docs/guide/usage/linter/rules/unicorn/no-null

Configuration file example to enable the unicorn/no-null rule with the 'error' severity.

```json
{
  "rules": {
    "unicorn/no-null": "error"
  }
}
```

--------------------------------

### Correct code example for no-dupe-keys

Source: https://oxc.rs/docs/guide/usage/linter/rules/eslint/no-dupe-keys

This example shows an object literal with unique keys, which passes the rule.

```javascript
var foo = {
  bar: "baz",
  qux: "qux",
};

```

--------------------------------

### Configuration example for esmodule option

Source: https://oxc.rs/docs/guide/usage/linter/rules/import/no-absolute-path

Shows an ES module import with an absolute path, which is reported when the `esmodule` option is enabled (default true).

```javascript
import foo from "/foo"; // reported
```

--------------------------------

### sortImports.partitionByComment example

Source: https://oxc.rs/docs/guide/usage/formatter/config-file-reference.html

Example of partitionByComment: when true, comments act as delimiters, creating separate import groups.

```js
import { b1, b2 } from "b";
// PARTITION
import { a } from "a";
import { c } from "c";
```

--------------------------------

### Variable initialization example

Source: https://oxc.rs/docs/guide/usage/linter/rules/eslint/init-declarations

Shows the difference between initializing a variable during declaration (`foo`) and assigning it later (`bar`).

```javascript
var foo = 1;
var bar;
if (foo) {
  bar = 1;
} else {
  bar = 2;
}

```

--------------------------------

### Enable rule via CLI

Source: https://oxc.rs/docs/guide/usage/linter/rules/react/checked-requires-onchange-or-readonly

Command-line example to enable the rule with --deny and --react-plugin flags.

```bash
oxlint --deny react/checked-requires-onchange-or-readonly --react-plugin
```

--------------------------------

### Incorrect code examples for typescript/no-extra-non-null-assertion

Source: https://oxc.rs/docs/guide/usage/linter/rules/typescript/no-extra-non-null-assertion

Examples of incorrect code for the rule, showing extra non-null assertions that are disallowed.

```ts
const foo: { bar: number } | null = null;
const bar = foo!!!.bar;

```

```ts
function foo(bar: number | undefined) {
  const bar: number = bar!!!;
}

```

```ts
function foo(bar?: { n: number }) {
  return bar!?.n;
}

```

--------------------------------

### CLI

Source: https://oxc.rs/docs/guide/usage/linter/rules/eslint/no-lonely-if

Enable the rule via CLI.

```bash
oxlint --deny no-lonely-if
```

--------------------------------

### Correct code examples for oxc/const-comparisons

Source: https://oxc.rs/docs/guide/usage/linter/rules/oxc/const-comparisons

Examples of code that correctly use comparisons, avoiding redundant or impossible logic.

```javascript
status_code >= 400 && status_code < 500;
500 <= status_code && 600 > status_code;
500 <= status_code && status_code <= 600;
a < b;
a <= b;
```

--------------------------------

### Enable unicorn/no-empty-file rule

Source: https://oxc.rs/docs/guide/usage/linter/rules/unicorn/no-empty-file

These configuration examples show how to enable the unicorn/no-empty-file rule using the .oxlintrc.json config file, the oxlint.config.ts config file, or the CLI flag --deny.

```json
{
  "rules": {
    "unicorn/no-empty-file": "error"
  }
}
```

```ts
import { defineConfig } from "oxlint";

export default defineConfig({
  rules: {
    "unicorn/no-empty-file": "error",
  },
});
```

```bash
oxlint --deny unicorn/no-empty-file
```

--------------------------------

### Enable react/display-name via .oxlintrc.json

Source: https://oxc.rs/docs/guide/usage/linter/rules/react/display-name

Configuration file example to enable the rule with 'error' severity.

```json
{
  "plugins": ["react"],
  "rules": {
    "react/display-name": "error"
  }
}
```

--------------------------------

### Correct code examples for jest/prefer-to-contain

Source: https://oxc.rs/docs/guide/usage/linter/rules/jest/prefer-to-contain

These examples show the recommended usage of toContain() and not.toContain() for array inclusion assertions.

```javascript
expect(a).toContain(b);
expect(a).not.toContain(b);
```
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