---
url: /docs/guide/usage/linter/rules/unicorn/prefer-set-has.md
---

### What it does

Prefer `Set#has()` over `Array#includes()` when checking for existence or non-existence.

### Why is this bad?

`Set#has()` is faster than `Array#includes()`.

### Examples

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

```js
const array = [1, 2, 3];
const hasValue = (value) => array.includes(value);
```

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

```js
const set = new Set([1, 2, 3]);
const hasValue = (value) => set.has(value);
```

```js
const array = [1, 2, 3];
const hasOne = array.includes(1);
```

## How to use

## Version

This rule was added in v0.13.2.

## References