# Enforce consistent case for text encoding identifiers

💼 This rule is enabled in the following [configs](https://github.com/sindresorhus/eslint-plugin-unicorn#recommended-config): ✅ `recommended`, ☑️ `unopinionated`.

🔧💡 This rule is automatically fixable by the [`--fix` CLI option](https://eslint.org/docs/latest/user-guide/command-line-interface#--fix) and manually fixable by [editor suggestions](https://eslint.org/docs/latest/use/core-concepts#rule-suggestions).

<!-- end auto-generated rule header -->
<!-- Do not manually modify this header. Run: `npm run fix:eslint-docs` -->

- Enforce `'utf8'` for [UTF-8](https://en.wikipedia.org/wiki/UTF-8) encoding.
- Enforce `'ascii'` for [ASCII](https://en.wikipedia.org/wiki/ASCII) encoding.

This rule only auto-fix encoding in `fs.readFile()` and `fs.readFileSync()`.

## Examples

```js
// ❌
await fs.readFile(file, 'UTF-8');

// ✅
await fs.readFile(file, 'utf8');
```

```js
// ❌
await fs.readFile(file, 'ASCII');

// ✅
await fs.readFile(file, 'ascii');
```

```js
// ❌
const string = buffer.toString('utf-8');

// ✅
const string = buffer.toString('utf8');
```

## Options

Type: `object`

### withDash

Type: `boolean`\
Default: `false`

Use WHATWG standard encoding notation with dashes (e.g., ⁠`utf-8` instead of `⁠utf8`).

```js
// ❌
/* eslint unicorn/text-encoding-identifier-case: ["error", {"withDash": true}] */
await fs.readFile(file, 'utf8');
```

```js
// ✅
/* eslint unicorn/text-encoding-identifier-case: ["error", {"withDash": true}] */
await fs.readFile(file, 'utf-8');
```