# Prefer negative index over `.length - index` when possible

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

🔧 This rule is automatically fixable by the [`--fix` CLI option](https://eslint.org/docs/latest/user-guide/command-line-interface#--fix).

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

Prefer negative index over calculating from `.length` for:

- [`String#slice()`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/slice)
- [`Array#slice()`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/slice)
- [`TypedArray#slice()`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray/slice)
- [`String#at()`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/at)
- [`Array#at()`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/at)
- [`TypedArray#at()`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray/at)
- [`Array#splice()`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/splice)
- [`Array#toSpliced()`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/toSpliced)
- [`Array#with()`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/with)
- [`TypedArray#with()`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray/with)
- [`TypedArray#subarray()`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray/subarray)

## Fail

```js
foo.slice(foo.length - 2, foo.length - 1);
```

```js
foo.splice(foo.length - 1, 1);
```

```js
foo.at(foo.length - 1);
```

```js
Array.prototype.slice.call(foo, foo.length - 2, foo.length - 1);
```

```js
Array.prototype.slice.apply(foo, [foo.length - 2, foo.length - 1]);
```

## Pass

```js
foo.slice(-2, -1);
```

```js
foo.splice(-1, 1);
```

```js
foo.at(-1);
```

```js
Array.prototype.slice.call(foo, -2, -1);
```

```js
Array.prototype.slice.apply(foo, [-2, -1]);
```

## Related rules

- [unicorn/prefer-at](./prefer-at.md)