---
title: maxLength
description: Creates a max length validation action.
source: /actions/maxLength/maxLength.ts
contributors:
  - fabian-hiller
  - depsimon
  - yslpn
---

import { ApiList, Link, Property } from '~/components';
import { properties } from './properties';

# maxLength

Creates a max length validation action.

```ts
const Action = v.maxLength<TInput, TRequirement, TMessage>(
  requirement,
  message
);
```

## Generics

- `TInput` <Property {...properties.TInput} />
- `TRequirement` <Property {...properties.TRequirement} />
- `TMessage` <Property {...properties.TMessage} />

## Parameters

- `requirement` <Property {...properties.requirement} />
- `message` <Property {...properties.message} />

### Explanation

With `maxLength` you can validate the length of a string or array. For strings, length is measured like JavaScript's `value.length`, i.e. by UTF-16 code units. For arrays, length is measured by the number of items. If the input does not match the `requirement`, you can use `message` to customize the error message.

> If you need to validate the maximum number of user-perceived characters, use <Link href="../maxGraphemes/">`maxGraphemes`</Link> instead.

## Returns

- `Action` <Property {...properties.Action} />

## Examples

The following examples show how `maxLength` can be used.

### Maximum string length

Schema to validate a string with a maximum length of 32 UTF-16 code units.

```ts
const MaxStringSchema = v.pipe(
  v.string(),
  v.maxLength(32, 'The string must not exceed 32 UTF-16 code units.')
);
```

### Maximum array length

Schema to validate an array with a maximum length of 5 items.

```ts
const MaxArraySchema = v.pipe(
  v.array(v.number()),
  v.maxLength(5, 'The array must not exceed 5 numbers.')
);
```

## Related

The following APIs can be combined with `maxLength`.

### Schemas

<ApiList
  items={['any', 'array', 'custom', 'instance', 'string', 'tuple', 'unknown']}
/>

### Methods

<ApiList items={['pipe']} />

### Actions

<ApiList items={['maxGraphemes']} />

### Utils

<ApiList items={['isOfKind', 'isOfType']} />
