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# no-unnecessary-array-flat-depth

[Added in v0.9.1](https://github.com/web-infra-dev/rslint/releases/tag/v0.9.1)
## Configuration

| Preset                              | Configured Value |
| ----------------------------------- | ---------------- |
| ✅ unicornPlugin.configs.recommended | `"error"`        |


```ts title=rslint.config.ts
import { defineConfig, unicornPlugin } from '@rslint/core';

export default defineConfig([
  unicornPlugin.configs.recommended,
  {
    rules: {
      'unicorn/no-unnecessary-array-flat-depth': 'error',
    },
  },
]);
```

## Rule Details

Disallow passing `1` as the `depth` argument to `Array#flat()`.

The default depth of `Array#flat()` is already `1`, so writing the argument
explicitly is redundant.

Examples of **incorrect** code for this rule:

```javascript
const nested = [1, [2, 3]];
nested.flat(1);
```

Examples of **correct** code for this rule:

```javascript
const nested = [1, [2, 3]];
nested.flat();
```

Depths other than the numeric literal `1` are left unchanged:

```javascript
nested.flat(2);
nested.flat(Infinity);
nested.flat(depth);
```

## Original Documentation

- [eslint-plugin-unicorn: no-unnecessary-array-flat-depth](https://github.com/sindresorhus/eslint-plugin-unicorn/blob/v74.0.0/docs/rules/no-unnecessary-array-flat-depth.md)
- [Source code](https://github.com/sindresorhus/eslint-plugin-unicorn/blob/v74.0.0/rules/no-unnecessary-array-flat-depth.js)