---
url: /docs/guide/usage/linter/rules/unicorn/no-instanceof-array.md
---

### What it does

Require `Array.isArray()` instead of `instanceof Array`.

### Why is this bad?

The `instanceof Array` check doesn't work across realms/contexts.
For example, frames/windows in browsers or the `vm` module in Node.js.

### Examples

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

```javascript
array instanceof Array;
[1, 2, 3] instanceof Array;
```

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

```javascript
Array.isArray(array);
Array.isArray([1, 2, 3]);
```

## How to use

## Version

This rule was added in v0.0.8.

## References