npm package: @ratatat/ink
Description: ink-fast implementation inside the Ratatat monorepo
Author: Vadim Demedes
Latest version: 6.8.0

[![](https://raw.githubusercontent.com/vshymanskyy/StandWithUkraine/main/banner2-direct.svg)](https://github.com/vshymanskyy/StandWithUkraine/blob/main/docs/README.md)

---

<div align="center">
	<br>
	<br>
	<img width="240" alt="Ink" src="media/logo.png">
	<br>
	<br>
	<br>
</div>

> React for CLIs. Build and test your CLI output using components.

> `ink-fast` is a performance-focused fork of Ink.
>
> Perf toolkit: [`benchmark/render/README.md`](./benchmark/render/README.md), [`benchmark/render/perf-notes.md`](./benchmark/render/perf-notes.md)
>
> Technical deep dive: [`TECHNICAL-README.md`](./TECHNICAL-README.md)
>
> [!NOTE]
> In this monorepo, the package name is `@ratatat/ink`.
> Use `@ratatat/ink` for install/import commands.

### Proof-of-concept benchmark (Ink vs ink-fast)

Snapshot: [`benchmark/render/results/ink-vs-ink-fast-243e962-vs-4451bab.json`](./benchmark/render/results/ink-vs-ink-fast-243e962-vs-4451bab.json)

| Workload | Ink (ms) | ink-fast (ms) |       Delta |    Speedup |
| -------- | -------: | ------------: | ----------: | ---------: |
| dense    |   2.1688 |        0.1580 | **-92.71%** | **13.72x** |
| unicode  |   5.6133 |        5.1659 |  **-7.97%** |  **1.09x** |
| sparse   |   0.3933 |        0.0461 | **-88.28%** |  **8.53x** |

Geometric mean speedup: **5.03x**

[![Build Status](https://github.com/geoffmiller/ink-fast/workflows/test/badge.svg)](https://github.com/geoffmiller/ink-fast/actions)
[![npm](https://img.shields.io/npm/dm/ink-fast?logo=npm)](https://npmjs.com/package/ink-fast)

Ink provides the same component-based UI building experience that React offers in the browser, but for command-line apps.
It uses [Yoga](https://github.com/facebook/yoga) to build Flexbox layouts in the terminal, so most CSS-like properties are available in Ink as well.
If you are already familiar with React, you already know Ink.

Since Ink is a React renderer, all features of React are supported.
Head over to the [React](https://reactjs.org) website for documentation on how to use it.
Only Ink's methods are documented in this readme.

---

<div align="center">
	<p>
		<p>
			<sup>
				<a href="https://opencollective.com/vadimdemedes">My open source work is supported by the community ❤️</a>
			</sup>
		</p>
	</p>
</div>

## Install

```sh
npm install @ratatat/ink react
```

> [!NOTE]
> Many snippets below are inherited from upstream Ink docs and use `ink`/`ink-fast` in import lines.
> For this package, replace those imports with `@ratatat/ink`.

## Usage

```jsx
import React, {useState, useEffect} from 'react';
import {render, Text} from '@ratatat/ink';

const Counter = () => {
	const [counter, setCounter] = useState(0);

	useEffect(() => {
		const timer = setInterval(() => {
			setCounter(previousCounter => previousCounter + 1);
		}, 100);

		return () => {
			clearInterval(timer);
		};
	}, []);

	return <Text color="green">{counter} tests passed</Text>;
};

render(<Counter />);
```

<img src="media/demo.svg" width="600">

## Who's Using Ink?

- [Claude Code](https://github.com/anthropics/claude-code) - An agentic coding tool made by Anthropic.
- [Gemini CLI](https://github.com/google-gemini/gemini-cli) - An agentic coding tool made by Google.
- [GitHub Copilot CLI](https://github.com/features/copilot/cli) - Just say what you want the shell to do.
- [Canva CLI](https://www.canva.dev/docs/apps/canva-cli/) - CLI for creating and managing Canva Apps.
- [Cloudflare's Wrangler](https://github.com/cloudflare/wrangler2) - The CLI for Cloudflare Workers.
- [Linear](https://linear.app) - Linear built an internal CLI for managing deployments, configs, and other housekeeping tasks.
- [Gatsby](https://www.gatsbyjs.org) - Gatsby is a modern web framework for blazing-fast websites.
- [tap](https://node-tap.org) - A Test-Anything-Protocol library for JavaScript.
- [Terraform CDK](https://github.com/hashicorp/terraform-cdk) - Cloud Development Kit (CDK) for HashiCorp Terraform.
- [Specify CLI](https://specifyapp.com) - Automate the distribution of your design tokens.
- [Twilio's SIGNAL](https://github.com/twilio-labs/plugin-signal2020) - CLI for Twilio's SIGNAL conference. [Blog post](https://www.twilio.com/blog/building-conference-cli-in-react).
- [Typewriter](https://github.com/segmentio/typewriter) - Generates strongly-typed [Segment](https://segment.com) analytics clients from arbitrary JSON Schema.
- [Prisma](https://www.prisma.io) - The unified data layer for modern applications.
- [Blitz](https://blitzjs.com) - The Fullstack React Framework.
- [New York Times](https://github.com/nytimes/kyt) - NYT uses Ink's `kyt` - a toolkit that encapsulates and manages the configuration for web apps.
- [tink](https://github.com/npm/tink) - A next-generation runtime and package manager.
- [Inkle](https://github.com/jrr/inkle) - A Wordle game.
- [loki](https://github.com/oblador/loki) - Visual regression testing tool for Storybook.
- [Bit](https://github.com/teambit/bit) - Build, distribute, and collaborate on components.
- [Remirror](https://github.com/remirror/remirror) - Your friendly, world-class editor toolkit.
- [Prime](https://github.com/birkir/prime) - Open-source GraphQL CMS.
- [emoj](https://github.com/sindresorhus/emoj) - Find relevant emojis.
- [emma](https://github.com/maticzav/emma-cli) - Find and install npm packages easily.
- [npm-check-extras](https://github.com/akgondber/npm-check-extras) - Check for outdated and unused dependencies, and run update/delete actions on selected ones.
- [swiff](https://github.com/simple-integrated-marketing/swiff) - Multi-environment command-line tools for time-saving web developers.
- [share](https://github.com/marionebl/share-cli) - Share files quickly.
- [Kubelive](https://github.com/ameerthehacker/kubelive) - A CLI for Kubernetes that provides live data about the cluster and its resources.
- [changelog-view](https://github.com/jdeniau/changelog-view) - View changelogs.
- [cfpush](https://github.com/mamachanko/cfpush) - Interactive Cloud Foundry tutorial.
- [startd](https://github.com/mgrip/startd) - Turn your React component into a web app.
- [wiki-cli](https://github.com/hexrcs/wiki-cli) - Search Wikipedia and read article summaries.
- [garson](https://github.com/goliney/garson) - Build interactive, config-based command-line interfaces.
- [git-contrib-calendar](https://github.com/giannisp/git-contrib-calendar) - Display a contributions calendar for any Git repository.
- [gitgud](https://github.com/GitGud-org/GitGud) - Interactive command-line GUI for Git.
- [Autarky](https://github.com/pranshuchittora/autarky) - Find and delete old `node_modules` directories to free up disk space.
- [fast-cli](https://github.com/sindresorhus/fast-cli) - Test your download and upload speeds.
- [tasuku](https://github.com/privatenumber/tasuku) - Minimal task runner.
- [mnswpr](https://github.com/mordv/mnswpr) - A Minesweeper game.
- [lrn](https://github.com/krychu/lrn) - Learning by repetition.
- [turdle](https://github.com/mynameisankit/turdle) - A Wordle game.
- [Shopify CLI](https://github.com/Shopify/cli) - Build apps, themes, and storefronts for the Shopify platform.
- [ToDesktop CLI](https://www.todesktop.com/electron) - All-in-one platform for building Electron apps.
- [Walle](https://github.com/Pobepto/walle) - A full-featured crypto wallet for EVM networks.
- [Sudoku](https://github.com/mrozio13pl/sudoku-in-terminal) - A Sudoku game.
- [Sea Trader](https://github.com/zyishai/sea-trader) - A Taipan!-inspired trading simulator game.
- [srtd](https://github.com/t1mmen/srtd) - Live-reloading SQL templates for Supabase projects.
- [tweakcc](https://github.com/Piebald-AI/tweakcc) - Customize your Claude Code styling.
- [argonaut](https://github.com/darksworm/argonaut) - Manage Argo CD resources.
- [Qodo Command](https://github.com/qodo-ai/command) - Build, run, and manage AI agents.
- [Nanocoder](https://github.com/nano-collective/nanocoder) - A community-built, local-first AI coding agent with multi-provider support.
- [dev3000](https://github.com/vercel-labs/dev3000) - An AI agent MCP orchestrator and developer browser.
- [Neovate Code](https://github.com/neovateai/neovate-code) - An agentic coding tool made by AntGroup.
- [instagram-cli](https://github.com/supreme-gg-gg/instagram-cli) - Instagram client.
- [ElevenLabs CLI](https://github.com/elevenlabs/cli) - ElevenLabs agents client.
- [SSH AI Chat](https://github.com/miantiao-me/ssh-ai-chat) - Chat with AI over SSH.

_(PRs welcome. Append new entries at the end. Repos must have 100+ stars and showcase Ink beyond a basic list picker.)_

## Contents

- [Getting Started](#getting-started)
- [App Lifecycle](#app-lifecycle)
- [Components](#components)
  - [`<Text>`](#text)
  - [`<Box>`](#box)
  - [`<Newline>`](#newline)
  - [`<Spacer>`](#spacer)
  - [`<Static>`](#static)
  - [`<Transform>`](#transform)
- [Hooks](#hooks)
  - [`useInput`](#useinputinputhandler-options)
  - [`usePaste`](#usepastehandler-options)
  - [`useApp`](#useapp)
  - [`useStdin`](#usestdin)
  - [`useStdout`](#usestdout)
  - [`useBoxMetrics`](#useboxmetricsref)
  - [`useStderr`](#usestderr)
  - [`useWindowSize`](#usewindowsize)
  - [`useFocus`](#usefocusoptions)
  - [`useFocusManager`](#usefocusmanager)
  - [`useCursor`](#usecursor)
- [API](#api)
- [Testing](#testing)
- [Using React Devtools](#using-react-devtools)
- [Screen Reader Support](#screen-reader-support)
- [Useful Components](#useful-components)
- [Useful Hooks](#useful-hooks)
- [Recipes](#recipes)
- [Examples](#examples)
- [Continuous Integration](#continuous-integration)

## Getting Started

Use [create-ink-app](https://github.com/vadimdemedes/create-ink-app) to quickly scaffold a new Ink-based CLI.

```sh
npx create-ink-app my-ink-cli
```

Alternatively, create a TypeScript project:

```sh
npx create-ink-app --typescript my-ink-cli
```

<details><summary>Manual JavaScript setup</summary>
<p>
Ink requires the same Babel setup as you would do for regular React-based apps in the browser.

Set up Babel with a React preset to ensure all examples in this readme work as expected.
After [installing Babel](https://babeljs.io/docs/en/usage), install `@babel/preset-react` and insert the following configuration in `babel.config.json`:

```sh
npm install --save-dev @babel/preset-react
```

```json
{
	"presets": ["@babel/preset-react"]
}
```

Next, create a file `source.js`, where you'll type code that uses Ink:

```jsx
import React from 'react';
import {render, Text} from 'ink-fast';

const Demo = () => <Text>Hello World</Text>;

render(<Demo />);
```

Then, transpile this file with Babel:

```sh
npx babel source.js -o cli.js
```

Now you can run `cli.js` with Node.js:

```sh
node cli
```

If you don't like transpiling files during development, you can use [import-jsx](https://github.com/vadimdemedes/import-jsx) or [@esbuild-kit/esm-loader](https://github.com/esbuild-kit/esm-loader) to `import` a JSX file and transpile it on the fly.

</p>
</details>

Ink uses [Yoga](https://github.com/facebook/yoga), a Flexbox layout engine, to build great user interfaces for your CLIs using familiar CSS-like properties you've used when building apps for the browser.
It's important to remember that each element is a Flexbox container.
Think of it as if every `<div>` in the browser had `display: flex`.
See [`<Box>`](#box) built-in component below for documentation on how to use Flexbox layouts in Ink.
Note that all text must be wrapped in a [`<Text>`](#text) component.

## App Lifecycle

An Ink app is a Node.js process, so it stays alive only while there is active work in the event loop (timers, pending promises, [`useInput`](#useinputinputhandler-options) listening on `stdin`, etc.). If your component tree has no async work, the app will render once and exit immediately.

To exit the app, press **Ctrl+C** (enabled by default via [`exitOnCtrlC`](#exitonctrlc)), call [`exit()`](#exiterrororresult) from [`useApp`](#useapp) inside a component, or call [`unmount()`](#unmount) on the object returned by [`render()`](#rendertree-options).

Use [`waitUntilExit()`](#waituntilexit) to run code after the app is unmounted:

```jsx
const {waitUntilExit} = render(<MyApp />);

await waitUntilExit();

console.log('App exited');
```

## Components

### `<Text>`

This component can display text and change its style to make it bold, underlined, italic, or strikethrough.

```jsx
import {render, Text} from 'ink-fast';

const Example = () => (
	<>
		<Text color="green">I am green</Text>
		<Text color="black" backgroundColor="white">
			I am black on white
		</Text>
		<Text color="#ffffff">I am white</Text>
		<Text bold>I am bold</Text>
		<Text italic>I am italic</Text>
		<Text underline>I am underline</Text>
		<Text strikethrough>I am strikethrough</Text>
		<Text inverse>I am inversed</Text>
	</>
);

render(<Example />);
```

> [!NOTE]
> `<Text>` allows only text nodes and nested `<Text>` components inside of it. For example, `<Box>` component can't be used inside `<Text>`.

#### color

Type: `string`

Change text color.
Ink uses [chalk](https://github.com/chalk/chalk) under the hood, so all its functionality is supported.

```jsx
<Text color="green">Green</Text>
<Text color="#005cc5">Blue</Text>
<Text color="rgb(232, 131, 136)">Red</Text>
```

<img src="media/text-color.jpg" width="247">

#### backgroundColor

Type: `string`

Same as `color` above, but for background.

```jsx
<Text backgroundColor="green" color="white">Green</Text>
<Text backgroundColor="#005cc5" color="white">Blue</Text>
<Text backgroundColor="rgb(232, 131, 136)" color="white">Red</Text>
```

<img src="media/text-backgroundColor.jpg" width="226">

#### dimColor

Type: `boolean`\
Default: `false`

Dim the color (make it less bright).

```jsx
<Text color="red" dimColor>
	Dimmed Red
</Text>
```

<img src="media/text-dimColor.jpg" width="138">

#### bold

Type: `boolean`\
Default: `false`

Make the text bold.

#### italic

Type: `boolean`\
Default: `false`

Make the text italic.

#### underline

Type: `boolean`\
Default: `false`

Make the text underlined.

#### strikethrough

Type: `boolean`\
Default: `false`

Make the text crossed with a line.

#### inverse

Type: `boolean`\
Default: `false`

Invert background and foreground colors.

```jsx
<Text inverse color="yellow">
	Inversed Yellow
</Text>
```

<img src="media/text-inverse.jpg" width="138">

#### wrap

Type: `string`\
Allowed values: `wrap` `truncate` `truncate-start` `truncate-middle` `truncate-end`\
Default: `wrap`

This property tells Ink to wrap or truncate text if its width is larger than the container.
If `wrap` is passed (the default), Ink will wrap text and split it into multiple lines.
If `truncate-*` is passed, Ink will truncate text instead, resulting in one line of text with the rest cut off.

```jsx
<Box width={7}>
	<Text>Hello World</Text>
</Box>
//=> 'Hello\nWorld'

// `truncate` is an alias to `truncate-end`
<Box width={7}>
	<Text wrap="truncate">Hello World</Text>
</Box>
//=> 'Hello…'

<Box width={7}>
	<Text wrap="truncate-middle">Hello World</Text>
</Box>
//=> 'He…ld'

<Box width={7}>
	<Text wrap="truncate-start">Hello World</Text>
</Box>
//=> '…World'
```

### `<Box>`

`<Box>` is an essential Ink component to build your layout.
It's like `<div style="display: flex">` in the browser.

```jsx
import {render, Box, Text} from 'ink';

const Example = () => (
	<Box margin={2}>
		<Text>This is a box with margin</Text>
	</Box>
);

render(<Example />);
```

#### Dimensions

##### width

Type: `number` `string`

Width of the element in spaces.
You can also set it as a percentage, which will calculate the width based on the width of the parent element.

```jsx
<Box width={4}>
	<Text>X</Text>
</Box>
//=> 'X   '
```

```jsx
<Box width={10}>
	<Box width="50%">
		<Text>X</Text>
	</Box>
	<Text>Y</Text>
</Box>
//=> 'X    Y'
```

##### height

Type: `number` `string`

Height of the element in lines (rows).
You can also set it as a percentage, which will calculate the height based on the height of the parent element.

```jsx
<Box height={4}>
	<Text>X</Text>
</Box>
//=> 'X\n\n\n'
```

```jsx
<Box height={6} flexDirection="column">
	<Box height="50%">
		<Text>X</Text>
	</Box>
	<Text>Y</Text>
</Box>
//=> 'X\n\n\nY\n\n'
```

##### minWidth

Type: `number`

Sets a minimum width of the element.
Percentages aren't supported yet; see https://github.com/facebook/yoga/issues/872.

##### minHeight

Type: `number` `string`

Sets a minimum height of the element in lines (rows).
You can also set it as a percentage, which will calculate the minimum height based on the height of the parent element.

##### maxWidth

Type: `number`

Sets a maximum width of the element.
Percentages aren't supported yet; see https://github.com/facebook/yoga/issues/872.

##### maxHeight

Type: `number` `string`

Sets a maximum height of the element in lines (rows).
You can also set it as a percentage, which will calculate the maximum height based on the height of the parent element.

##### aspectRatio

Type: `number`

Defines the aspect ratio (width/height) for the element.

Use it with at least one size constraint (`width`, `height`, `minHeight`, or `maxHeight`) so Ink can derive the missing dimension.

#### Padding

##### paddingTop

Type: `number`\
Default: `0`

Top padding.

##### paddingBottom

Type: `number`\
Default: `0`

Bottom padding.

##### paddingLeft

Type: `number`\
Default: `0`

Left padding.

##### paddingRight

Type: `number`\
Default: `0`

Right padding.

##### paddingX

Type: `number`\
Default: `0`

Horizontal padding. Equivalent to setting `paddingLeft` and `paddingRight`.

##### paddingY

Type: `number`\
Default: `0`

Vertical padding. Equivalent to setting `paddingTop` and `paddingBottom`.

##### padding

Type: `number`\
Default: `0`

Padding on all sides. Equivalent to setting `paddingTop`, `paddingBottom`, `paddingLeft` and `paddingRight`.

```jsx
<Box paddingTop={2}><Text>Top</Text></Box>
<Box paddingBottom={2}><Text>Bottom</Text></Box>
<Box paddingLeft={2}><Text>Left</Text></Box>
<Box paddingRight={2}><Text>Right</Text></Box>
<Box paddingX={2}><Text>Left and right</Text></Box>
<Box paddingY={2}><Text>Top and bottom</Text></Box>
<Box padding={2}><Text>Top, bottom, left and right</Text></Box>
```

#### Margin

##### marginTop

Type: `number`\
Default: `0`

Top margin.

##### marginBottom

Type: `number`\
Default: `0`

Bottom margin.

##### marginLeft

Type: `number`\
Default: `0`

Left margin.

##### marginRight

Type: `number`\
Default: `0`

Right margin.

##### marginX

Type: `number`\
Default: `0`

Horizontal margin. Equivalent to setting `marginLeft` and `marginRight`.

##### marginY

Type: `number`\
Default: `0`

Vertical margin. Equivalent to setting `marginTop` and `marginBottom`.

##### margin

Type: `number`\
Default: `0`

Margin on all sides. Equivalent to setting `marginTop`, `marginBottom`, `marginLeft` and `marginRight`.

```jsx
<Box marginTop={2}><Text>Top</Text></Box>
<Box marginBottom={2}><Text>Bottom</Text></Box>
<Box marginLeft={2}><Text>Left</Text></Box>
<Box marginRight={2}><Text>Right</Text></Box>
<Box marginX={2}><Text>Left and right</Text></Box>
<Box marginY={2}><Text>Top and bottom</Text></Box>
<Box margin={2}><Text>Top, bottom, left and right</Text></Box>
```

#### Gap

#### gap

Type: `number`\
Default: `0`

Size of the gap between an element's columns and rows. A shorthand for `columnGap` and `rowGap`.

```jsx
<Box gap={1} width={3} flexWrap="wrap">
	<Text>A</Text>
	<Text>B</Text>
	<Text>C</Text>
</Box>
// A B
//
// C
```

#### columnGap

Type: `number`\
Default: `0`

Size of the gap between an element's columns.

```jsx
<Box columnGap={1}>
	<Text>A</Text>
	<Text>B</Text>
</Box>
// A B
```

#### rowGap

Type: `number`\
Default: `0`

Size of the gap between an element's rows.

```jsx
<Box flexDirection="column" rowGap={1}>
	<Text>A</Text>
	<Text>B</Text>
</Box>
// A
//
// B
```

#### Flex

##### flexGrow

Type: `number`\
Default: `0`

See [flex-grow](https://css-tricks.com/almanac/properties/f/flex-grow/).

```jsx
<Box>
	<Text>Label:</Text>
	<Box flexGrow={1}>
		<Text>Fills all remaining space</Text>
	</Box>
</Box>
```

##### flexShrink

Type: `number`\
Default: `1`

See [flex-shrink](https://css-tricks.com/almanac/properties/f/flex-shrink/).

```jsx
<Box width={20}>
	<Box flexShrink={2} width={10}>
		<Text>Will be 1/4</Text>
	</Box>
	<Box width={10}>
		<Text>Will be 3/4</Text>
	</Box>
</Box>
```

##### flexBasis

Type: `number` `string`

See [flex-basis](https://css-tricks.com/almanac/properties/f/flex-basis/).

```jsx
<Box width={6}>
	<Box flexBasis={3}>
		<Text>X</Text>
	</Box>
	<Text>Y</Text>
</Box>
//=> 'X  Y'
```

```jsx
<Box width={6}>
	<Box flexBasis="50%">
		<Text>X</Text>
	</Box>
	<Text>Y</Text>
</Box>
//=> 'X  Y'
```

##### flexDirection

Type: `string`\
Allowed values: `row` `row-reverse` `column` `column-reverse`

See [flex-direction](https://css-tricks.com/almanac/properties/f/flex-direction/).

```jsx
<Box>
	<Box marginRight={1}>
		<Text>X</Text>
	</Box>
	<Text>Y</Text>
</Box>
// X Y

<Box flexDirection="row-reverse">
	<Text>X</Text>
	<Box marginRight={1}>
		<Text>Y</Text>
	</Box>
</Box>
// Y X

<Box flexDirection="column">
	<Text>X</Text>
	<Text>Y</Text>
</Box>
// X
// Y

<Box flexDirection="column-reverse">
	<Text>X</Text>
	<Text>Y</Text>
</Box>
// Y
// X
```

##### flexWrap

Type: `string`\
Allowed values: `nowrap` `wrap` `wrap-reverse`

See [flex-wrap](https://css-tricks.com/almanac/properties/f/flex-wrap/).

```jsx
<Box width={2} flexWrap="wrap">
	<Text>A</Text>
	<Text>BC</Text>
</Box>
// A
// B C
```

```jsx
<Box flexDirection="column" height={2} flexWrap="wrap">
	<Text>A</Text>
	<Text>B</Text>
	<Text>C</Text>
</Box>
// A C
// B
```

##### alignItems

Type: `string`\
Allowed values: `flex-start` `center` `flex-end` `stretch` `baseline`

See [align-items](https://css-tricks.com/almanac/properties/a/align-items/).

```jsx
<Box alignItems="flex-start">
	<Box marginRight={1}>
		<Text>X</Text>
	</Box>
	<Text>
		A
		<Newline/>
		B
		<Newline/>
		C
	</Text>
</Box>
// X A
//   B
//   C

<Box alignItems="center">
	<Box marginRight={1}>
		<Text>X</Text>
	</Box>
	<Text>
		A
		<Newline/>
		B
		<Newline/>
		C
	</Text>
</Box>
//   A
// X B
//   C

<Box alignItems="flex-end">
	<Box marginRight={1}>
		<Text>X</Text>
	</Box>
	<Text>
		A
		<Newline/>
		B
		<Newline/>
		C
	</Text>
</Box>
//   A
//   B
// X C
```

##### alignSelf

Type: `string`\
Default: `auto`\
Allowed values: `auto` `flex-start` `center` `flex-end` `stretch` `baseline`

See [align-self](https://css-tricks.com/almanac/properties/a/align-self/).

```jsx
<Box height={3}>
	<Box alignSelf="flex-start">
		<Text>X</Text>
	</Box>
</Box>
// X
//
//

<Box height={3}>
	<Box alignSelf="center">
		<Text>X</Text>
	</Box>
</Box>
//
// X
//

<Box height={3}>
	<Box alignSelf="flex-end">
		<Text>X</Text>
	</Box>
</Box>
//
//
// X
```

##### alignContent

Type: `string`\
Default: `flex-start`\
Allowed values: `flex-start` `flex-end` `center` `stretch` `space-between` `space-around` `space-evenly`

Defines alignment between flex lines on the cross axis when `flexWrap` creates multiple lines.
See [align-content](https://css-tricks.com/almanac/properties/a/align-content/).
Unlike CSS (`stretch`), Ink defaults to `flex-start` so wrapped lines stay compact and fixed-height boxes don't gain unexpected empty rows unless you opt in to stretching.

##### justifyContent

Type: `string`\
Allowed values: `flex-start` `center` `flex-end` `space-between` `space-around` `space-evenly`

See [justify-content](https://css-tricks.com/almanac/properties/j/justify-content/).

```jsx
<Box justifyContent="flex-start">
	<Text>X</Text>
</Box>
// [X      ]

<Box justifyContent="center">
	<Text>X</Text>
</Box>
// [   X   ]

<Box justifyContent="flex-end">
	<Text>X</Text>
</Box>
// [      X]

<Box justifyContent="space-between">
	<Text>X</Text>
	<Text>Y</Text>
</Box>
// [X      Y]

<Box justifyContent="space-around">
	<Text>X</Text>
	<Text>Y</Text>
</Box>
// [  X   Y  ]

<Box justifyContent="space-evenly">
	<Text>X</Text>
	<Text>Y</Text>
</Box>
// [   X   Y   ]
```

#### Position

##### position

Type: `string`\
Allowed values: `relative` `absolute` `static`\
Default: `relative`

Controls how the element is positioned.

When `position` is `static`, `top`, `right`, `bottom`, and `left` are ignored.

##### top

Type: `number` `string`

Top offset for positioned elements.
You can also set it as a percentage of the parent size.

##### right

Type: `number` `string`

Right offset for positioned elements.
You can also set it as a percentage of the parent size.

##### bottom

Type: `number` `string`

Bottom offset for positioned elements.
You can also set it as a percentage of the parent size.

##### left

Type: `number` `string`

Left offset for positioned elements.
You can also set it as a percentage of the parent size.

#### Visibility

##### display

Type: `string`\
Allowed values: `flex` `none`\
Default: `flex`

Set this property to `none` to hide the element.

##### overflowX

Type: `string`\
Allowed values: `visible` `hidden`\
Default: `visible`

Behavior for an element's overflow in the horizontal direction.

##### overflowY

Type: `string`\
Allowed values: `visible` `hidden`\
Default: `visible`

Behavior for an element's overflow in the vertical direction.

##### overflow

Type: `string`\
Allowed values: `visible` `hidden`\
Default: `visible`

A shortcut for setting `overflowX` and `overflowY` at the same time.

#### Borders

##### borderStyle

Type: `string`\
Allowed values: `single` `double` `round` `bold` `singleDouble` `doubleSingle` `classic` | `BoxStyle`

Add a border with a specified style.
If `borderStyle` is `undefined` (the default), no border will be added.
Ink uses border styles from the [`cli-boxes`](https://github.com/sindresorhus/cli-boxes) module.

```jsx
<Box flexDirection="column">
	<Box>
		<Box borderStyle="single" marginRight={2}>
			<Text>single</Text>
		</Box>

		<Box borderStyle="double" marginRight={2}>
			<Text>double</Text>
		</Box>

		<Box borderStyle="round" marginRight={2}>
			<Text>round</Text>
		</Box>

		<Box borderStyle="bold">
			<Text>bold</Text>
		</Box>
	</Box>

	<Box marginTop={1}>
		<Box borderStyle="singleDouble" marginRight={2}>
			<Text>singleDouble</Text>
		</Box>

		<Box borderStyle="doubleSingle" marginRight={2}>
			<Text>doubleSingle</Text>
		</Box>

		<Box borderStyle="classic">
			<Text>classic</Text>
		</Box>
	</Box>
</Box>
```

<img src="media/box-borderStyle.jpg" width="521">

Alternatively, pass a custom border style like so:

```jsx
<Box
	borderStyle={{
		topLeft: '↘',
		top: '↓',
		topRight: '↙',
		left: '→',
		bottomLeft: '↗',
		bottom: '↑',
		bottomRight: '↖',
		right: '←',
	}}
>
	<Text>Custom</Text>
</Box>
```

See example in [examples/borders](examples/borders/borders.tsx).

##### borderColor

Type: `string`

Change border color.
A shorthand for setting `borderTopColor`, `borderRightColor`, `borderBottomColor`, and `borderLeftColor`.

```jsx
<Box borderStyle="round" borderColor="green">
	<Text>Green Rounded Box</Text>
</Box>
```

<img src="media/box-borderColor.jpg" width="228">

##### borderTopColor

Type: `string`

Change top border color.
Accepts the same values as [`color`](#color) in `<Text>` component.

```jsx
<Box borderStyle="round" borderTopColor="green">
	<Text>Hello world</Text>
</Box>
```

##### borderRightColor

Type: `string`

Change the right border color.
Accepts the same values as [`color`](#color) in `<Text>` component.

```jsx
<Box borderStyle="round" borderRightColor="green">
	<Text>Hello world</Text>
</Box>
```

##### borderBottomColor

Type: `string`

Change the bottom border color.
Accepts the same values as [`color`](#color) in `<Text>` component.

```jsx
<Box borderStyle="round" borderBottomColor="green">
	<Text>Hello world</Text>
</Box>
```

##### borderLeftColor

Type: `string`

Change the left border color.
Accepts the same values as [`color`](#color) in `<Text>` component.

```jsx
<Box borderStyle="round" borderLeftColor="green">
	<Text>Hello world</Text>
</Box>
```

##### borderDimColor

Type: `boolean`\
Default: `false`

Dim the border color.
A shorthand for setting `borderTopDimColor`, `borderBottomDimColor`, `borderLeftDimColor`, and `borderRightDimColor`.

```jsx
<Box borderStyle="round" borderDimColor>
	<Text>Hello world</Text>
</Box>
```

##### borderTopDimColor

Type: `boolean`\
Default: `false`

Dim the top border color.

```jsx
<Box borderStyle="round" borderTopDimColor>
	<Text>Hello world</Text>
</Box>
```

##### borderBottomDimColor

Type: `boolean`\
Default: `false`

Dim the bottom border color.

```jsx
<Box borderStyle="round" borderBottomDimColor>
	<Text>Hello world</Text>
</Box>
```

##### borderLeftDimColor

Type: `boolean`\
Default: `false`

Dim the left border color.

```jsx
<Box borderStyle="round" borderLeftDimColor>
	<Text>Hello world</Text>
</Box>
```

##### borderRightDimColor

Type: `boolean`\
Default: `false`

Dim the right border color.

```jsx
<Box borderStyle="round" borderRightDimColor>
	<Text>Hello world</Text>
</Box>
```

##### borderTop

Type: `boolean`\
Default: `true`

Determines whether the top border is visible.

##### borderRight

Type: `boolean`\
Default: `true`

Determines whether the right border is visible.

##### borderBottom

Type: `boolean`\
Default: `true`

Determines whether the bottom border is visible.

##### borderLeft

Type: `boolean`\
Default: `true`

Determines whether the left border is visible.

#### Background

##### backgroundColor

Type: `string`

Background color for the element.

Accepts the same values as [`color`](#color) in the `<Text>` component.

```jsx
<Box flexDirection="column">
	<Box backgroundColor="red" width={20} height={5} alignSelf="flex-start">
		<Text>Red background</Text>
	</Box>

	<Box
		backgroundColor="#FF8800"
		width={20}
		height={3}
		marginTop={1}
		alignSelf="flex-start"
	>
		<Text>Orange background</Text>
	</Box>

	<Box
		backgroundColor="rgb(0, 255, 0)"
		width={20}
		height={3}
		marginTop={1}
		alignSelf="flex-start"
	>
		<Text>Green background</Text>
	</Box>
</Box>
```

The background color fills the entire `<Box>` area and is inherited by child `<Text>` components unless they specify their own `backgroundColor`.

```jsx
<Box backgroundColor="blue" alignSelf="flex-start">
	<Text>Blue inherited </Text>
	<Text backgroundColor="yellow">Yellow override </Text>
	<Text>Blue inherited again</Text>
</Box>
```

Background colors work with borders and padding:

```jsx
<Box
	backgroundColor="cyan"
	borderStyle="round"
	padding={1}
	alignSelf="flex-start"
>
	<Text>Background with border and padding</Text>
</Box>
```

See example in [examples/box-backgrounds](examples/box-backgrounds/box-backgrounds.tsx).

### `<Newline>`

Adds one or more newline (`\n`) characters.
Must be used within `<Text>` components.

#### count

Type: `number`\
Default: `1`

Number of newlines to insert.

```jsx
import {render, Text, Newline} from 'ink';

const Example = () => (
	<Text>
		<Text color="green">Hello</Text>
		<Newline />
		<Text color="red">World</Text>
	</Text>
);

render(<Example />);
```

Output:

```
Hello
World
```

### `<Spacer>`

A flexible space that expands along the major axis of its containing layout.
It's useful as a shortcut for filling all the available space between elements.

For example, using `<Spacer>` in a `<Box>` with default flex direction (`row`) will position "Left" on the left side and will push "Right" to the right side.

```jsx
import {render, Box, Text, Spacer} from 'ink';

const Example = () => (
	<Box>
		<Text>Left</Text>
		<Spacer />
		<Text>Right</Text>
	</Box>
);

render(<Example />);
```

In a vertical flex direction (`column`), it will position "Top" at the top of the container and push "Bottom" to the bottom.
Note that the container needs to be tall enough to see this in effect.

```jsx
import {render, Box, Text, Spacer} from 'ink';

const Example = () => (
	<Box flexDirection="column" height={10}>
		<Text>Top</Text>
		<Spacer />
		<Text>Bottom</Text>
	</Box>
);

render(<Example />);
```

### `<Static>`

`<Static>` component permanently renders its output above everything else.
It's useful for displaying activity like completed tasks or logs - things that
don't change after they're rendered (hence the name "Static").

It's preferred to use `<Static>` for use cases like these when you can't know
or control the number of items that need to be rendered.

For example, [Tap](https://github.com/tapjs/node-tap) uses `<Static>` to display
a list of completed tests. [Gatsby](https://github.com/gatsbyjs/gatsby) uses it
to display a list of generated pages while still displaying a live progress bar.

```jsx
import React, {useState, useEffect} from 'react';
import {render, Static, Box, Text} from 'ink';

const Example = () => {
	const [tests, setTests] = useState([]);

	useEffect(() => {
		let completedTests = 0;
		let timer;

		const run = () => {
			// Fake 10 completed tests
			if (completedTests++ < 10) {
				setTests(previousTests => [
					...previousTests,
					{
						id: previousTests.length,
						title: `Test #${previousTests.length + 1}`,
					},
				]);

				timer = setTimeout(run, 100);
			}
		};

		run();

		return () => {
			clearTimeout(timer);
		};
	}, []);

	return (
		<>
			{/* This part will be rendered once to the terminal */}
			<Static items={tests}>
				{test => (
					<Box key={test.id}>
						<Text color="green">✔ {test.title}</Text>
					</Box>
				)}
			</Static>

			{/* This part keeps updating as state changes */}
			<Box marginTop={1}>
				<Text dimColor>Completed tests: {tests.length}</Text>
			</Box>
		</>
	);
};

render(<Example />);
```

> [!NOTE]
> `<Static>` only renders new items in the `items` prop and ignores items
> that were previously rendered. This means that when you add new items to the `items`
> array, changes you make to previous items will not trigger a rerender.

See [examples/static](examples/static/static.tsx) for an example usage of `<Static>` component.

#### items

Type: `Array`

Array of items of any type to render using the function you pass as a component child.

#### style

Type: `object`

Styles to apply to a container of child elements.
See [`<Box>`](#box) for supported properties.

```jsx
<Static items={...} style={{padding: 1}}>
	{...}
</Static>
```

#### children(item)

Type: `Function`

Function that is called to render every item in the `items` array.
The first argument is the item itself, and the second argument is the index of that item in the
`items` array.

Note that a `key` must be assigned to the root component.

```jsx
<Static items={['a', 'b', 'c']}>
	{(item, index) => {
		// This function is called for every item in ['a', 'b', 'c']
		// `item` is 'a', 'b', 'c'
		// `index` is 0, 1, 2
		return (
			<Box key={index}>
				<Text>Item: {item}</Text>
			</Box>
		);
	}}
</Static>
```

### `<Transform>`

Transform a string representation of React components before they're written to output.
For example, you might want to apply a [gradient to text](https://github.com/sindresorhus/ink-gradient), [add a clickable link](https://github.com/sindresorhus/ink-link), or [create some text effects](https://github.com/sindresorhus/ink-big-text).
These use cases can't accept React nodes as input; they expect a string.
That's what the `<Transform>` component does: it gives you an output string of its child components and lets you transform it in any way.

> [!NOTE]
> `<Transform>` must be applied only to `<Text>` children components and shouldn't change the dimensions of the output; otherwise, the layout will be incorrect.

> [!IMPORTANT]
> When children use `<Text>` styling props (e.g. `color`, `bold`), the string passed to `transform` will contain [ANSI escape codes](https://en.wikipedia.org/wiki/ANSI_escape_code). If your transform manipulates whitespace or does string operations like `.trim()`, you may need to use ANSI-aware methods (e.g. from [`slice-ansi`](https://github.com/chalk/slice-ansi) or [`strip-ansi`](https://github.com/chalk/strip-ansi)).

```jsx
import {render, Transform} from 'ink';

const Example = () => (
	<Transform transform={output => output.toUpperCase()}>
		<Text>Hello World</Text>
	</Transform>
);

render(<Example />);
```

Since the `transform` function converts all characters to uppercase, the final output rendered to the terminal will be "HELLO WORLD", not "Hello World".

When the output wraps to multiple lines, it can be helpful to know which line is being processed.

For example, to implement a hanging indent component, you can indent all the lines except for the first.

```jsx
import {render, Transform} from 'ink';

const HangingIndent = ({indent = 4, children}) => (
	<Transform
		transform={(line, index) =>
			index === 0 ? line : ' '.repeat(indent) + line
		}
	>
		{children}
	</Transform>
);

const text =
	'WHEN I WROTE the following pages, or rather the bulk of them, ' +
	'I lived alone, in the woods, a mile from any neighbor, in a ' +
	'house which I had built myself, on the shore of Walden Pond, ' +
	'in Concord, Massachusetts, and earned my living by the labor ' +
	'of my hands only. I lived there two years and two months. At ' +
	'present I am a sojourner in civilized life again.';

render(<HangingIndent indent={4}>{text}</HangingIndent>);
```

#### transform(outputLine, index)

Type: `Function`

Function that transforms children output.
It accepts children and must return transformed children as well.

##### children

Type: `string`

Output of child components.

##### index

Type: `number`

The zero-indexed line number of the line that's currently being transformed.

## Hooks

### useInput(inputHandler, options?)

A React hook that returns `void` and handles user input.
It's a more convenient alternative to using `useStdin` and listening for `data` events.
The callback you pass to `useInput` is called for each character when the user enters any input.
However, if the user pastes text and it's more than one character, the callback will be called only once, and the whole string will be passed as `input`.
You can find a full example of using `useInput` at [examples/use-input](examples/use-input/use-input.tsx).

```jsx
import {useInput} from 'ink';

const UserInput = () => {
	useInput((input, key) => {
		if (input === 'q') {
			// Exit program
		}

		if (key.leftArrow) {
			// Left arrow key pressed
		}
	});

	return …
};
```

#### inputHandler(input, key)

Type: `Function`

The handler function that you pass to `useInput` receives two arguments:

##### input

Type: `string`

The input that the program received.

##### key

Type: `object`

Handy information about a key that was pressed.

###### key.leftArrow

###### key.rightArrow

###### key.upArrow

###### key.downArrow

Type: `boolean`\
Default: `false`

If an arrow key was pressed, the corresponding property will be `true`.
For example, if the user presses the left arrow key, `key.leftArrow` equals `true`.

###### key.return

Type: `boolean`\
Default: `false`

Return (Enter) key was pressed.

###### key.escape

Type: `boolean`\
Default: `false`

Escape key was pressed.

###### key.ctrl

Type: `boolean`\
Default: `false`

Ctrl key was pressed.

###### key.shift

Type: `boolean`\
Default: `false`

Shift key was pressed.

###### key.tab

Type: `boolean`\
Default: `false`

Tab key was pressed.

###### key.backspace

Type: `boolean`\
Default: `false`

Backspace key was pressed.

###### key.delete

Type: `boolean`\
Default: `false`

Delete key was pressed.

###### key.pageDown

###### key.pageUp

Type: `boolean`\
Default: `false`

If the Page Up or Page Down key was pressed, the corresponding property will be `true`.
For example, if the user presses Page Down, `key.pageDown` equals `true`.

###### key.home

###### key.end

Type: `boolean`\
Default: `false`

If the Home or End key was pressed, the corresponding property will be `true`.
For example, if the user presses End, `key.end` equals `true`.

###### key.meta

Type: `boolean`\
Default: `false`

[Meta key](https://en.wikipedia.org/wiki/Meta_key) was pressed.

###### key.super

Type: `boolean`\
Default: `false`

Super key (Cmd on macOS, Win on Windows) was pressed. Requires [kitty keyboard protocol](#kittykeyboard).

###### key.hyper

Type: `boolean`\
Default: `false`

Hyper key was pressed. Requires [kitty keyboard protocol](#kittykeyboard).

###### key.capsLock

Type: `boolean`\
Default: `false`

Caps Lock was active. Requires [kitty keyboard protocol](#kittykeyboard).

###### key.numLock

Type: `boolean`\
Default: `false`

Num Lock was active. Requires [kitty keyboard protocol](#kittykeyboard).

###### key.eventType

Type: `'press' | 'repeat' | 'release'`\
Default: `undefined`

The type of key event. Only available with [kitty keyboard protocol](#kittykeyboard). Without the protocol, this property is `undefined`.

#### options

Type: `object`

##### isActive

Type: `boolean`\
Default: `true`

Enable or disable capturing of user input.
Useful when there are multiple `useInput` hooks used at once to avoid handling the same input several times.

### usePaste(handler, options?)

A React hook that calls `handler` whenever the user pastes text. Bracketed paste mode (`\x1b[?2004h`) is automatically enabled while the hook is active, so pasted text arrives as a single string rather than being misinterpreted as individual key presses.

`usePaste` and `useInput` can be used together in the same component. They operate on separate event channels, so paste content is never forwarded to `useInput` handlers when `usePaste` is active.

```jsx
import {useInput, usePaste} from 'ink';

const MyInput = () => {
	useInput((input, key) => {
		// Only receives typed characters and key events, not pasted text.
		if (key.return) {
			// Submit
		}
	});

	usePaste((text) => {
		// Receives the full pasted string, including newlines.
		console.log('Pasted:', text);
	});

	return …
};
```

#### handler(text)

Type: `Function`

Called with the full pasted string whenever the user pastes text. The string is delivered verbatim — newlines, escape sequences, and other special characters are preserved exactly as pasted.

##### text

Type: `string`

The pasted text.

#### options

Type: `object`

##### isActive

Type: `boolean`\
Default: `true`

Enable or disable the paste handler. Useful when multiple components use `usePaste` and only one should be active at a time.

### useApp()

A React hook that returns app lifecycle methods.

#### exit(errorOrResult?)

Type: `Function`

Exit (unmount) the whole Ink app.

##### errorOrResult

Type: `Error | unknown`

Optional value that controls how [`waitUntilExit`](#waituntilexit) settles:

- `exit()` resolves with `undefined`.
- `exit(error)` rejects when `error` is an `Error`.
- `exit(value)` resolves with `value`.

```js
import {useEffect} from 'react';
import {useApp} from 'ink';

const Example = () => {
	const {exit} = useApp();

	// Exit the app after 5 seconds
	useEffect(() => {
		setTimeout(() => {
			exit();
		}, 5000);
	}, [exit]);

	return …
};
```

#### waitUntilRenderFlush()

Type: `Function`

Returns a promise that settles after pending render output is flushed to stdout.

```js
import {useEffect} from 'react';
import {useApp} from 'ink';

const Example = () => {
	const {waitUntilRenderFlush} = useApp();

	useEffect(() => {
		void (async () => {
			await waitUntilRenderFlush();
			runNextCommand();
		})();
	}, [waitUntilRenderFlush]);

	return …;
};
```

### useStdin()

A React hook that returns the stdin stream and stdin-related utilities.

#### stdin

Type: `stream.Readable`\
Default: `process.stdin`

The stdin stream passed to `render()` in `options.stdin`, or `process.stdin` by default.
Useful if your app needs to handle user input.

```js
import {useStdin} from 'ink';

const Example = () => {
	const {stdin} = useStdin();

	return …
};
```

#### isRawModeSupported

Type: `boolean`

A boolean flag determining if the current `stdin` supports `setRawMode`.
A component using `setRawMode` might want to use `isRawModeSupported` to nicely fall back in environments where raw mode is not supported.

```jsx
import {useStdin} from 'ink';

const Example = () => {
	const {isRawModeSupported} = useStdin();

	return isRawModeSupported ? (
		<MyInputComponent />
	) : (
		<MyComponentThatDoesntUseInput />
	);
};
```

#### setRawMode(isRawModeEnabled)

Type: `function`

##### isRawModeEnabled

Type: `boolean`

See [`setRawMode`](https://nodejs.org/api/tty.html#tty_readstream_setrawmode_mode).
Ink exposes this function to be able to handle <kbd>Ctrl</kbd>+<kbd>C</kbd>, that's why you should use Ink's `setRawMode` instead of `process.stdin.setRawMode`.

**Warning:** This function will throw unless the current `stdin` supports `setRawMode`. Use [`isRawModeSupported`](#israwmodesupported) to detect `setRawMode` support.

```js
import {useStdin} from 'ink';

const Example = () => {
	const {setRawMode} = useStdin();

	useEffect(() => {
		setRawMode(true);

		return () => {
			setRawMode(false);
		};
	});

	return …
};
```

### useStdout()

A React hook that returns the stdout stream where Ink renders your app and stdout-related utilities.

#### stdout

Type: `stream.Writable`\
Default: `process.stdout`

```js
import {useStdout} from 'ink';

const Example = () => {
	const {stdout} = useStdout();

	return …
};
```

#### write(data)

Write any string to stdout while preserving Ink's output.
It's useful when you want to display external information outside of Ink's rendering and ensure there's no conflict between the two.
It's similar to `<Static>`, except it can't accept components; it only works with strings.

##### data

Type: `string`

Data to write to stdout.

```js
import {useStdout} from 'ink';

const Example = () => {
	const {write} = useStdout();

	useEffect(() => {
		// Write a single message to stdout, above Ink's output
		write('Hello from Ink to stdout\n');
	}, []);

	return …
};
```

See additional usage example in [examples/use-stdout](examples/use-stdout/use-stdout.tsx).

### useBoxMetrics(ref)

A React hook that returns the current layout metrics for a tracked box element.
It updates when layout changes (for example terminal resize, sibling/content changes, or position changes).

Use `hasMeasured` to detect when the currently tracked element has been measured.

#### ref

Type: `React.RefObject<DOMElement>`

A ref to the `<Box>` element to track.

```jsx
import {useRef} from 'react';
import {Box, Text, useBoxMetrics} from 'ink';

const Example = () => {
	const ref = useRef(null);
	const {width, height, left, top, hasMeasured} = useBoxMetrics(ref);

	return (
		<Box ref={ref}>
			<Text>
				{hasMeasured ? `${width}x${height} at ${left},${top}` : 'Measuring...'}
			</Text>
		</Box>
	);
};
```

#### width

Type: `number`

Element width.

#### height

Type: `number`

Element height.

#### left

Type: `number`

Distance from the left edge of the parent.

#### top

Type: `number`

Distance from the top edge of the parent.

#### hasMeasured

Type: `boolean`

Whether the currently tracked element has been measured.

> [!NOTE]
> The hook returns `{width: 0, height: 0, left: 0, top: 0}` until the first layout pass completes. It also returns zeros when the tracked ref is detached.

### useStderr()

A React hook that returns the stderr stream and stderr-related utilities.

#### stderr

Type: `stream.Writable`\
Default: `process.stderr`

Stderr stream.

```js
import {useStderr} from 'ink';

const Example = () => {
	const {stderr} = useStderr();

	return …
};
```

#### write(data)

Write any string to stderr while preserving Ink's output.

It's useful when you want to display external information outside of Ink's rendering and ensure there's no conflict between the two.
It's similar to `<Static>`, except it can't accept components; it only works with strings.

##### data

Type: `string`

Data to write to stderr.

```js
import {useStderr} from 'ink';

const Example = () => {
	const {write} = useStderr();

	useEffect(() => {
		// Write a single message to stderr, above Ink's output
		write('Hello from Ink to stderr\n');
	}, []);

	return …
};
```

### useWindowSize()

A React hook that returns the current terminal dimensions and re-renders the component whenever the terminal is resized.

```js
import {Text, useWindowSize} from 'ink';

const Example = () => {
	const {columns, rows} = useWindowSize();

	return (
		<Text>
			{columns}x{rows}
		</Text>
	);
};
```

#### columns

Type: `number`

Number of columns (horizontal character cells).

#### rows

Type: `number`

Number of rows (vertical character cells).

### useFocus(options?)

A React hook that returns focus state and focus controls for the current component.
A component that uses the `useFocus` hook becomes "focusable" to Ink, so when the user presses <kbd>Tab</kbd>, Ink will switch focus to this component.
If there are multiple components that execute the `useFocus` hook, focus will be given to them in the order in which these components are rendered.
This hook returns an object with an `isFocused` boolean property, which determines whether this component is focused.

#### options

##### autoFocus

Type: `boolean`\
Default: `false`

Auto-focus this component if there's no active (focused) component right now.

##### isActive

Type: `boolean`\
Default: `true`

Enable or disable this component's focus, while still maintaining its position in the list of focusable components.
This is useful for inputs that are temporarily disabled.

##### id

Type: `string`\
Required: `false`

Set a component's focus ID, which can be used to programmatically focus the component. This is useful for large interfaces with many focusable elements to avoid having to cycle through all of them.

```jsx
import {render, useFocus, Text} from 'ink';

const Example = () => {
	const {isFocused} = useFocus();

	return <Text>{isFocused ? 'I am focused' : 'I am not focused'}</Text>;
};

render(<Example />);
```

See example in [examples/use-focus](examples/use-focus/use-focus.tsx) and [examples/use-focus-with-id](examples/use-focus-with-id/use-focus-with-id.tsx).

### useFocusManager()

A React hook that returns methods to manage focus across focusable components.

#### enableFocus()

Enable focus management for all components.

> [!NOTE]
> You don't need to call this method manually unless you've disabled focus management. Focus management is enabled by default.

```js
import {useFocusManager} from 'ink';

const Example = () => {
	const {enableFocus} = useFocusManager();

	useEffect(() => {
		enableFocus();
	}, []);

	return …
};
```

#### disableFocus()

Disable focus management for all components.
The currently active component (if there's one) will lose its focus.

```js
import {useFocusManager} from 'ink';

const Example = () => {
	const {disableFocus} = useFocusManager();

	useEffect(() => {
		disableFocus();
	}, []);

	return …
};
```

#### focusNext()

Switch focus to the next focusable component.
If there's no active component right now, focus will be given to the first focusable component.
If the active component is the last in the list of focusable components, focus will be switched to the first focusable component.

> [!NOTE]
> Ink calls this method when user presses <kbd>Tab</kbd>.

```js
import {useFocusManager} from 'ink';

const Example = () => {
	const {focusNext} = useFocusManager();

	useEffect(() => {
		focusNext();
	}, []);

	return …
};
```

#### focusPrevious()

Switch focus to the previous focusable component.
If there's no active component right now, focus will be given to the first focusable component.
If the active component is the first in the list of focusable components, focus will be switched to the last focusable component.

> [!NOTE]
> Ink calls this method when user presses <kbd>Shift</kbd>+<kbd>Tab</kbd>.

```js
import {useFocusManager} from 'ink';

const Example = () => {
	const {focusPrevious} = useFocusManager();

	useEffect(() => {
		focusPrevious();
	}, []);

	return …
};
```

#### focus(id)

##### id

Type: `string`

Switch focus to the component with the given [`id`](#id).
If there's no component with that ID, focus is not changed.

```js
import {useFocusManager, useInput} from 'ink';

const Example = () => {
	const {focus} = useFocusManager();

	useInput(input => {
		if (input === 's') {
			// Focus the component with focus ID 'someId'
			focus('someId');
		}
	});

	return …
};
```

#### activeId

Type: `string | undefined`

The ID of the currently focused component, or `undefined` if no component is focused.

```js
import {Text, useFocusManager} from 'ink';

const Example = () => {
	const {activeId} = useFocusManager();

	return <Text>Focused: {activeId ?? 'none'}</Text>;
};
```

### useCursor()

A React hook that returns methods to control the terminal cursor position after each render.
This is essential for IME (Input Method Editor) support, where the composing character is displayed at the cursor location.

```jsx
import {useState} from 'react';
import {Box, Text, useCursor} from 'ink';
import stringWidth from 'string-width';

const TextInput = () => {
	const [text, setText] = useState('');
	const {setCursorPosition} = useCursor();

	const prompt = '> ';
	setCursorPosition({x: stringWidth(prompt + text), y: 1});

	return (
		<Box flexDirection="column">
			<Text>Type here:</Text>
			<Text>
				{prompt}
				{text}
			</Text>
		</Box>
	);
};
```

#### setCursorPosition(position)

Set the cursor position relative to the Ink output. Pass `undefined` to hide the cursor.

##### position

Type: `object | undefined`

Use [`string-width`](https://github.com/sindresorhus/string-width) to calculate `x` for strings containing wide characters (CJK, emoji).

See a full example at [examples/cursor-ime](examples/cursor-ime/cursor-ime.tsx).

###### x

Type: `number`

Column position (0-based).

###### y

Type: `number`

Row position from the top of the Ink output (0 = first line).

### useIsScreenReaderEnabled()

A React hook that returns whether a screen reader is enabled.
This is useful when you want to render different output for screen readers.

```jsx
import {useIsScreenReaderEnabled, Text} from 'ink';

const Example = () => {
	const isScreenReaderEnabled = useIsScreenReaderEnabled();

	return (
		<Text>
			{isScreenReaderEnabled
				? 'Screen reader is enabled'
				: 'Screen reader is disabled'}
		</Text>
	);
};
```

## API

#### render(tree, options?)

Returns: [`Instance`](#instance)

Mount a component and render the output.

##### tree

Type: `ReactNode`

##### options

Type: `object`

###### stdout

Type: `stream.Writable`\
Default: `process.stdout`

Output stream where the app will be rendered.

###### stdin

Type: `stream.Readable`\
Default: `process.stdin`

Input stream where app will listen for input.

###### stderr

Type: `stream.Writable`\
Default: `process.stderr`

Error stream.

###### exitOnCtrlC

Type: `boolean`\
Default: `true`

Configure whether Ink should listen for Ctrl+C keyboard input and exit the app.
This is needed in case `process.stdin` is in [raw mode](https://nodejs.org/api/tty.html#tty_readstream_setrawmode_mode), because then Ctrl+C is ignored by default and the process is expected to handle it manually.

###### patchConsole

Type: `boolean`\
Default: `true`

Patch console methods to ensure console output doesn't mix with Ink's output.
When any of the `console.*` methods are called (like `console.log()`), Ink intercepts their output, clears the main output, renders output from the console method, and then rerenders the main output again.
That way, both are visible and don't overlap each other.

Once unmount starts, Ink restores the native console before React cleanup runs. Teardown-time `console.*` output then follows the normal console behavior instead of being rerouted through Ink.

This functionality is powered by [patch-console](https://github.com/vadimdemedes/patch-console), so if you need to disable Ink's interception of output but want to build something custom, you can use that.

###### onRender

Type: `({renderTime: number}) => void`\
Default: `undefined`

Runs the given callback after each render and re-render with render metrics.
This callback runs after Ink commits a frame, but it does not wait for `stdout`/`stderr` stream callbacks.
To run code after output is flushed, use [`waitUntilRenderFlush()`](#waituntilrenderflush).

###### isScreenReaderEnabled

Type: `boolean`\
Default: `process.env['INK_SCREEN_READER'] === 'true'`

Enable screen reader support. See [Screen Reader Support](#screen-reader-support).

###### debug

Type: `boolean`\
Default: `false`

If `true`, each update will be rendered as separate output, without replacing the previous one.

###### maxFps

Type: `number`\
Default: `30`

Maximum frames per second for render updates.
This controls how frequently the UI can update to prevent excessive re-rendering.
Higher values allow more frequent updates but may impact performance.
Setting it to a lower value may be useful for components that update very frequently, to reduce CPU usage.

###### incrementalRendering

Type: `boolean`\
Default: `false`

Enable incremental rendering mode which only updates changed lines instead of redrawing the entire output.
This can reduce flickering and improve performance for frequently updating UIs.

###### concurrent

Type: `boolean`\
Default: `false`

Enable React Concurrent Rendering mode.

When enabled:

- Suspense boundaries work correctly with async data fetching
- `useTransition` and `useDeferredValue` hooks are fully functional
- Updates can be interrupted for higher priority work

```jsx
render(<MyApp />, {concurrent: true});
```

> [!NOTE]
> Concurrent mode changes the timing of renders. Some tests may need to use `act()` to properly await updates. Reusing the same stdout across multiple `render()` calls without unmounting is unsupported. Call `unmount()` first if you need to change the rendering mode or create a fresh instance.

###### interactive

Type: `boolean`\
Default: `true` (`false` if in CI (detected via [`is-in-ci`](https://github.com/sindresorhus/is-in-ci)) or `stdout.isTTY` is falsy)

Override automatic interactive mode detection.

By default, Ink detects whether the environment is interactive based on CI detection and `stdout.isTTY`. When non-interactive, Ink skips terminal-specific features like ANSI erase sequences, cursor manipulation, synchronized output, resize handling, and kitty keyboard auto-detection. Only the final frame of non-static output is written at unmount.

Most users should not need to set this option. Use it when you have your own "interactive" detection logic that differs from the built-in behavior.

> [!NOTE]
> Reusing the same stdout across multiple `render()` calls without unmounting is unsupported. Call `unmount()` first if you need to change this option or create a fresh instance.

```jsx
// Use your own detection logic
const isInteractive = myCustomDetection();
render(<MyApp />, {interactive: isInteractive});
```

###### alternateScreen

Type: `boolean`\
Default: `false`

Render the app in the terminal's alternate screen buffer. When enabled, the app renders on a separate screen, and the original terminal content is restored when the app exits. This is the same mechanism used by programs like vim, htop, and less.

Note: The terminal's scrollback buffer is not available while in the alternate screen. This is standard terminal behavior; programs like vim use the alternate screen specifically to avoid polluting the user's scrollback history.

Ink intentionally treats alternate-screen teardown output as disposable. It does not preserve or replay teardown-time frames, hook writes, or `console.*` output after restoring the primary screen.

Only works in interactive mode. Ignored when `interactive` is `false` or in a non-interactive environment (CI, piped stdout).

> [!NOTE]
> Reusing the same stdout across multiple `render()` calls without unmounting is unsupported. Call `unmount()` first if you need to change this option or create a fresh instance.

```jsx
render(<MyApp />, {alternateScreen: true});
```

###### kittyKeyboard

Type: `object`\
Default: `undefined`

Enable the [kitty keyboard protocol](https://sw.kovidgoyal.net/kitty/keyboard-protocol/) for enhanced keyboard input handling. When enabled, terminals that support the protocol will report additional key information including `super`, `hyper`, `capsLock`, `numLock` modifiers and `eventType` (press/repeat/release).

```jsx
import {render} from 'ink';

render(<MyApp />, {kittyKeyboard: {mode: 'auto'}});
```

```jsx
import {render} from 'ink';

render(<MyApp />, {
	kittyKeyboard: {
		mode: 'enabled',
		flags: ['disambiguateEscapeCodes', 'reportEventTypes'],
	},
});
```

**kittyKeyboard.mode**

Type: `'auto' | 'enabled' | 'disabled'`\
Default: `'auto'`

- `'auto'`: Detect terminal support using a heuristic precheck (known terminals like kitty, WezTerm, Ghostty) followed by a protocol query confirmation (`CSI ? u`). The protocol is only enabled if the terminal responds to the query within a short timeout.
- `'enabled'`: Force enable the protocol. Both stdin and stdout must be TTYs.
- `'disabled'`: Never enable the protocol.

**kittyKeyboard.flags**

Type: `string[]`\
Default: `['disambiguateEscapeCodes']`

Protocol flags to request from the terminal. Pass an array of flag name strings.

Available flags:

- `'disambiguateEscapeCodes'` - Disambiguate escape codes
- `'reportEventTypes'` - Report key press, repeat, and release events
- `'reportAlternateKeys'` - Report alternate key encodings
- `'reportAllKeysAsEscapeCodes'` - Report all keys as escape codes
- `'reportAssociatedText'` - Report associated text with key events

**Behavior notes**

When the kitty keyboard protocol is enabled, input handling changes in several ways:

- **Non-printable keys produce empty input.** Keys like function keys (F1-F35), modifier-only keys (Shift, Control, Super), media keys, Caps Lock, Print Screen, and similar keys will not produce any text in the `input` parameter of `useInput`. They can still be detected via the `key` object properties.
- **Ctrl+letter shortcuts work as expected.** When the terminal sends `Ctrl+letter` as codepoint 1-26 (the kitty CSI-u alternate form), `input` is set to the letter name (e.g. `'c'` for `Ctrl+C`) and `key.ctrl` is `true`. This ensures `exitOnCtrlC` and custom `Ctrl+letter` handlers continue to work regardless of which codepoint form the terminal uses.
- **Key disambiguation.** The protocol allows the terminal to distinguish between keys that normally produce the same escape sequence. For example:
  - `Ctrl+I` vs `Tab` - without the protocol, both produce the same byte (`\x09`). With the protocol, they are reported as distinct keys.
  - `Shift+Enter` vs `Enter` - the shift modifier is correctly reported.
  - `Escape` key vs `Ctrl+[` - these are disambiguated.
- **Event types.** With the `reportEventTypes` flag, key press, repeat, and release events are distinguished via `key.eventType`.

#### renderToString(tree, options?)

Returns: `string`

Render a React element to a string synchronously. Unlike `render()`, this function does not write to stdout, does not set up any terminal event listeners, and returns the rendered output as a string.

Useful for generating documentation, writing output to files, testing, or any scenario where you need the rendered output as a string without starting a persistent terminal application.

```jsx
import {renderToString, Text, Box} from 'ink';

const output = renderToString(
	<Box padding={1}>
		<Text color="green">Hello World</Text>
	</Box>,
);

console.log(output);
```

**Notes:**

- Terminal-specific hooks (`useInput`, `useStdin`, `useStdout`, `useStderr`, `useWindowSize`, `useApp`, `useFocus`, `useFocusManager`) return default no-op values since there is no terminal session. They will not throw, but they will not function as in a live terminal.
- `useEffect` callbacks will execute during rendering (due to synchronous rendering mode), but state updates they trigger will not affect the returned output, which reflects the initial render.
- `useLayoutEffect` callbacks fire synchronously during commit, so state updates they trigger **will** be reflected in the output.
- The `<Static>` component is supported — its output is prepended to the dynamic output.
- If a component throws during rendering, the error is propagated to the caller after cleanup.

##### tree

Type: `ReactNode`

##### options

Type: `object`

###### columns

Type: `number`\
Default: `80`

Width of the virtual terminal in columns. Controls where text wrapping occurs.

```jsx
const output = renderToString(<Text>{'A'.repeat(100)}</Text>, {
	columns: 40,
});
// Text wraps at 40 columns
```

#### Instance

This is the object that `render()` returns.

##### rerender(tree)

Replace the previous root node with a new one or update the props of the current root node.

###### tree

Type: `ReactNode`

```jsx
// Update props of the root node
const {rerender} = render(<Counter count={1} />);
rerender(<Counter count={2} />);

// Replace root node
const {rerender} = render(<OldCounter />);
rerender(<NewCounter />);
```

##### unmount()

Manually unmount the whole Ink app.

```jsx
const {unmount} = render(<MyApp />);
unmount();
```

##### waitUntilExit()

Returns a promise that settles when the app is unmounted.

It resolves with the value passed to `exit(value)` and rejects with the error passed to `exit(error)`.
When `unmount()` is called manually, it settles after unmount-related stdout writes complete.

```jsx
const {unmount, waitUntilExit} = ren