---
url: /docs/guide/usage/linter/rules/typescript/array-type.md
---

### What it does

Require consistently using either `T[]` or `Array<T>` for arrays.

### Why is this bad?

Using the `Array` type directly is not idiomatic. Instead, use the array type `T[]` or `Array<T>`.

### Examples

Examples of **incorrect** code for this rule (with default configuration):

```typescript
const arr: Array<number> = new Array<number>();
const readonlyArr: ReadonlyArray<number> = [1, 2, 3];
```

Examples of **correct** code for this rule (with default configuration):

```typescript
const arr: number[] = new Array<number>();
const readonlyArr: readonly number[] = [1, 2, 3];
```

## Configuration

This rule accepts a configuration object with the following properties:

### default

type: `"array" | "array-simple" | "generic"`

default: `"array"`

The array type expected for mutable cases.

#### `"array"`

Enforce using `T[]` for all array types.

Example of **incorrect** code for this option:

```ts
const arr: Array<number> = new Array<number>();
```

Example of **correct** code for this option:

```ts
const arr: number[] = new Array<number>();
```

#### `"array-simple"`

Enforce using `T[]` for simple types, and `Array<T>` for complex types.

Example of **incorrect** code for this option:

```ts
const a: (string | number)[] = ["a", "b"];
const b: { prop: string }[] = [{ prop: "a" }];
const c: Array<MyType> = ["a", "b"];
const d: Array<string> = ["a", "b"];
```

Example of **correct** code for this option:

```ts
const a: Array<string | number> = ["a", "b"];
const b: Array<{ prop: string }> = [{ prop: "a" }];
const c: string[] = ["a", "b"];
const d: MyType[] = ["a", "b"];
```

#### `"generic"`

Enforce using `Array<T>` for all array types.

Example of **incorrect** code for this option:

```ts
const arr: number[] = new Array<number>();
```

Example of **correct** code for this option:

```ts
const arr: Array<number> = new Array<number>();
```

### readonly

type: `"array" | "array-simple" | "generic"`

default: `null`

The array type expected for readonly cases. If omitted, the value for `default` will be used.

## How to use

## Version

This rule was added in v0.2.8.

## References