Ecosyste.ms: Awesome

An open API service indexing awesome lists of open source software.

Awesome Lists | Featured Topics | Projects

https://github.com/vadimdemedes/ink

🌈 React for interactive command-line apps
https://github.com/vadimdemedes/ink

cli command-line flexbox interactive javascript react

Last synced: 11 days ago
JSON representation

🌈 React for interactive command-line apps

Awesome Lists containing this project

README 

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



---





	


	


	Ink

	


	


	





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



[![Build Status](https://github.com/vadimdemedes/ink/workflows/test/badge.svg)](https://github.com/vadimdemedes/ink/actions)

[![npm](https://img.shields.io/npm/dm/ink?logo=npm)](https://npmjs.com/package/ink)



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 props are available in Ink as well.

If you are already familiar with React, you already know Ink.



Since Ink is a React renderer, it means that all features of React are supported.

Head over to [React](https://reactjs.org) website for documentation on how to use it.

Only Ink's methods will be documented in this readme.



**Note:** This is documentation for Ink 4 and 5. If you're looking for docs on Ink 3, check out [this release](https://github.com/vadimdemedes/ink/tree/v3.2.0).



---





	


		




			

				My open source work is supported by the community ❤️

			

		


	




## Install



```sh

npm install ink react

```



## Usage



```jsx

import React, {useState, useEffect} from 'react';

import {render, Text} from 'ink';



const Counter = () => {

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



	useEffect(() => {

		const timer = setInterval(() => {

			setCounter(previousCounter => previousCounter + 1);

		}, 100);



		return () => {

			clearInterval(timer);

		};

	}, []);



	return {counter} tests passed;

};



render();

```






You can also check it out live on [repl.it sandbox](https://ink-counter-demo.vadimdemedes.repl.run/).

Feel free to play around with the code and fork this repl at [https://repl.it/@vadimdemedes/ink-counter-demo](https://repl.it/@vadimdemedes/ink-counter-demo).



## Who's Using Ink?



- [GitHub Copilot for CLI](https://githubnext.com/projects/copilot-cli) - Just say what you want the shell to do.

- [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) - CDK (Cloud Development Kit) 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 `kyt` - a toolkit that encapsulates and manages the configuration for web apps.

- [tink](https://github.com/npm/tink) - Next-generation runtime and package manager.

- [Inkle](https://github.com/jrr/inkle) - Wordle game.

- [loki](https://github.com/oblador/loki) - Visual regression testing 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.

- [Splash](https://github.com/Shopify/polaris-react/tree/master/scripts/splash) - Observe the splash zone of a change across the Shopify's [Polaris](https://polaris.shopify.com) component library.

- [emoj](https://github.com/sindresorhus/emoj) - Find relevant emojis.

- [emma](https://github.com/maticzav/emma-cli) - Find and install npm packages.

- [npm-check-extras](https://github.com/akgondber/npm-check-extras) - Check for outdated and unused dependencies, and run update/delete action over 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) - Quickly share files.

- [Kubelive](https://github.com/ameerthehacker/kubelive) - CLI for Kubernetes to provide live data about the cluster and its resources.

- [changelog-view](https://github.com/jdeniau/changelog-view) - View changelogs.

- [cfpush](https://github.com/mamachanko/cfpush) - An 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 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) - An interactive command-line GUI for Git.

- [Autarky](https://github.com/pranshuchittora/autarky) - Find and delete old `node_modules` directories in order to free up disk space.

- [fast-cli](https://github.com/sindresorhus/fast-cli) - Test your download and upload speed.

- [tasuku](https://github.com/privatenumber/tasuku) - Minimal task runner.

- [mnswpr](https://github.com/mordv/mnswpr) - Minesweeper game.

- [lrn](https://github.com/krychu/lrn) - Learning by repetition.

- [turdle](https://github.com/mynameisankit/turdle) - Wordle game.

- [Shopify CLI](https://github.com/Shopify/cli) - Build apps, themes, and storefronts for Shopify.

- [ToDesktop CLI](https://www.todesktop.com/electron) - An all-in-one platform for building Electron apps.

- [Walle](https://github.com/Pobepto/walle) - Full-featured crypto wallet for EVM networks.

- [Sudoku](https://github.com/mrozio13pl/sudoku-in-terminal) - Sudoku game.



## Contents



- [Getting Started](#getting-started)

- [Components](#components)

  - [``](#text)

  - [``](#box)

  - [``](#newline)

  - [``](#spacer)

  - [``](#static)

  - [``](#transform)

- [Hooks](#hooks)

  - [`useInput`](#useinputinputhandler-options)

  - [`useApp`](#useapp)

  - [`useStdin`](#usestdin)

  - [`useStdout`](#usestdout)

  - [`useStderr`](#usestderr)

  - [`useFocus`](#usefocusoptions)

  - [`useFocusManager`](#usefocusmanager)

- [API](#api)

- [Testing](#testing)

- [Using React Devtools](#using-react-devtools)

- [Useful Components](#useful-components)

- [Useful Hooks](#useful-hooks)

- [Examples](#examples)



## 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

```



Manual JavaScript setup



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';



const Demo = () => Hello World;



render();

```



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.






Ink uses [Yoga](https://github.com/facebook/yoga) - a Flexbox layout engine to build great user interfaces for your CLIs using familiar CSS-like props 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 each `
` in the browser had `display: flex`.

See [``](#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) component.



## Components



### ``



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



```jsx

import {render, Text} from 'ink';



const Example = () => (

	<>

		I am green

		

			I am black on white

		

		I am white

		I am bold

		I am italic

		I am underline

		I am strikethrough

		I am inversed

	>

);



render();

```



**Note:** `` allows only text nodes and nested `` components inside of it. For example, `` component can't be used inside ``.



#### color



Type: `string`



Change text color.

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



```jsx

Green

Blue

Red

```






#### backgroundColor



Type: `string`



Same as `color` above, but for background.



```jsx

Green

Blue

Red

```






#### dimColor



Type: `boolean`\

Default: `false`



Dim the color (emit a small amount of light).



```jsx



	Dimmed Red



```






#### 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`



Inverse background and foreground colors.



```jsx



	Inversed Yellow



```






#### 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 container.

If `wrap` is passed (by default), Ink will wrap text and split it into multiple lines.

If `truncate-*` is passed, Ink will truncate text instead, which will result in one line of text with the rest cut off.



```jsx



	Hello World



//=> 'Hello\nWorld'



// `truncate` is an alias to `truncate-end`



	Hello World



//=> 'Hello…'



	Hello World



//=> 'He…ld'



	Hello World



//=> '…World'

```



### ``



`` is an essential Ink component to build your layout.

It's like `
` in the browser.



```jsx

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



const Example = () => (

	

		This is a box with margin

	

);



render();

```



#### Dimensions



##### width



Type: `number` `string`



Width of the element in spaces.

You can also set it in percent, which will calculate the width based on the width of parent element.



```jsx



	X



//=> 'X   '

```



```jsx



	

		X

	

	Y



//=> 'X    Y'

```



##### height



Type: `number` `string`



Height of the element in lines (rows).

You can also set it in percent, which will calculate the height based on the height of parent element.



```jsx



	X



//=> 'X\n\n\n'

```



```jsx



	

		X

	

	Y



//=> '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`



Sets a minimum height of the element.

Percentages aren't supported yet, see https://github.com/facebook/yoga/issues/872.



#### 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

Top

Bottom

Left

Right

Left and right

Top and bottom

Top, bottom, left and right

```



#### 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

Top

Bottom

Left

Right

Left and right

Top and bottom

Top, bottom, left and right

```



#### Gap



#### gap



Type: `number`\

Default: `0`



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



```jsx



	A

	B

	C



// A B

//

// C

```



#### columnGap



Type: `number`\

Default: `0`



Size of the gap between an element's columns.



```jsx



	A

	B



// A B

```



#### rowGap



Type: `number`\

Default: `0`



Size of the gap between element's rows.



```jsx



	A

	B



// A

//

// B

```



#### Flex



##### flexGrow



Type: `number`\

Default: `0`



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



```jsx



	Label:

	

		Fills all remaining space

	



```



##### flexShrink



Type: `number`\

Default: `1`



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



```jsx



	

		Will be 1/4

	

	

		Will be 3/4

	



```



##### flexBasis



Type: `number` `string`



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



```jsx



	

		X

	

	Y



//=> 'X  Y'

```



```jsx



	

		X

	

	Y



//=> '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



	

		X

	

	Y



// X Y



	X

	

		Y

	



// Y X



	X

	Y



// X

// Y



	X

	Y



// Y

// X

```



##### flexWrap



Type: `string`\

Allowed values: `nowrap` `wrap` `wrap-reverse`



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



```jsx



	A

	BC



// A

// B C

```



```jsx



	A

	B

	C



// A C

// B

```



##### alignItems



Type: `string`\

Allowed values: `flex-start` `center` `flex-end`



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



```jsx



	

		X

	

	

		A

		

		B

		

		C

	



// X A

//   B

//   C



	

		X

	

	

		A

		

		B

		

		C

	



//   A

// X B

//   C



	

		X

	

	

		A

		

		B

		

		C

	



//   A

//   B

// X C

```



##### alignSelf



Type: `string`\

Default: `auto`\

Allowed values: `auto` `flex-start` `center` `flex-end`



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



```jsx



	

		X

	



// X

//

//



	

		X

	



//

// X

//



	

		X

	



//

//

// X

```



##### justifyContent



Type: `string`\

Allowed values: `flex-start` `center` `flex-end` `space-between` `space-around`



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



```jsx



	X



// [X      ]



	X



// [   X   ]



	X



// [      X]



	X

	Y



// [X      Y]



	X

	Y



// [  X   Y  ]

```



#### 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 horizontal direction.



##### overflowY



Type: `string`\

Allowed values: `visible` `hidden`\

Default: `visible`



Behavior for an element's overflow in vertical direction.



##### overflow



Type: `string`\

Allowed values: `visible` `hidden`\

Default: `visible`



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` (which it is by default), no border will be added.

Ink uses border styles from [`cli-boxes`](https://github.com/sindresorhus/cli-boxes) module.



```jsx



	

		

			single

		



		

			double

		



		

			round

		



		

			bold

		

	



	

		

			singleDouble

		



		

			doubleSingle

		



		

			classic

		

	



```






Alternatively, pass a custom border style like so:



```jsx



	Custom



```



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



##### borderColor



Type: `string`



Change border color.

Shorthand for setting `borderTopColor`, `borderRightColor`, `borderBottomColor` and `borderLeftColor`.



```jsx



	Green Rounded Box



```






##### borderTopColor



Type: `string`



Change top border color.

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



```jsx



	Hello world



```



##### borderRightColor



Type: `string`



Change right border color.

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



```jsx



	Hello world



```



##### borderRightColor



Type: `string`



Change right border color.

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



```jsx



	Hello world



```



##### borderBottomColor



Type: `string`



Change bottom border color.

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



```jsx



	Hello world



```



##### borderLeftColor



Type: `string`



Change left border color.

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



```jsx



	Hello world



```



##### borderDimColor



Type: `boolean`\

Default: `false`



Dim the border color.

Shorthand for setting `borderTopDimColor`, `borderBottomDimColor`, `borderLeftDimColor` and `borderRightDimColor`.



```jsx



	Hello world



```



##### borderTopDimColor



Type: `boolean`\

Default: `false`



Dim the top border color.



```jsx



	Hello world



```



##### borderBottomDimColor



Type: `boolean`\

Default: `false`



Dim the bottom border color.



```jsx



	Hello world



```



##### borderLeftDimColor



Type: `boolean`\

Default: `false`



Dim the left border color.



```jsx



	Hello world



```



##### borderRightDimColor



Type: `boolean`\

Default: `false`



Dim the right border color.



```jsx



	Hello world



```



##### borderTop



Type: `boolean`\

Default: `true`



Determines whether top border is visible.



##### borderRight



Type: `boolean`\

Default: `true`



Determines whether right border is visible.



##### borderBottom



Type: `boolean`\

Default: `true`



Determines whether bottom border is visible.



##### borderLeft



Type: `boolean`\

Default: `true`



Determines whether left border is visible.



### ``



Adds one or more newline (`\n`) characters.

Must be used within `` components.



#### count



Type: `number`\

Default: `1`



Number of newlines to insert.



```jsx

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



const Example = () => (

	

		Hello

		

		World

	

);



render();

```



Output:



```

Hello

World

```



### ``



A flexible space that expands along the major axis of its containing layout.

It's useful as a shortcut for filling all the available spaces between elements.



For example, using `` in a `` 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 = () => (

	

		Left

		

		Right

	

);



render();

```



In a vertical flex direction (`column`), it will position "Top" to the top of the container and push "Bottom" to the bottom of it.

Note, that container needs to be tall to enough to see this in effect.



```jsx

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



const Example = () => (

	

		Top

		

		Bottom

	

);



render();

```



### ``



`` component permanently renders its output above everything else.

It's useful for displaying activity like completed tasks or logs - things that

are not changing after they're rendered (hence the name "Static").



It's preferred to use `` for use cases like these, when you can't know

or control the amount of items that need to be rendered.



For example, [Tap](https://github.com/tapjs/node-tap) uses `` 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 */}

			

				{test => (

					

						✔ {test.title}

					

				)}

			



			{/* This part keeps updating as state changes */}

			

				Completed tests: {tests.length}

			

		>

	);

};



render();

```



**Note:** `` only renders new items in `items` prop and ignores items

that were previously rendered. This means that when you add new items to `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 `` component.



#### items



Type: `Array`



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



#### style



Type: `object`



Styles to apply to a container of child elements.

See [``](#box) for supported properties.



```jsx



	{...}



```



#### children(item)



Type: `Function`



Function that is called to render every item in `items` array.

First argument is an item itself and second argument is index of that item in

`items` array.



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



```jsx



	{(item, index) => {

		// This function is called for every item in ['a', 'b', 'c']

		// `item` is 'a', 'b', 'c'

		// `index` is 0, 1, 2

		return (

			

				Item: {item}

			

		);

	}}



```



### ``



Transform a string representation of React components before they are 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 are expecting a string.

That's what `` component does, it gives you an output string of its child components and lets you transform it in any way.



**Note:** `` must be applied only to `` children components and shouldn't change the dimensions of the output, otherwise layout will be incorrect.



```jsx

import {render, Transform} from 'ink';



const Example = () => (

	 output.toUpperCase()}>

		Hello World

	

);



render();

```



Since `transform` function converts all characters to upper case, final output that's 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 = ({content, indent = 4, children, ...props}) => (

	

			index === 0 ? line : ' '.repeat(indent) + line

		}

		{...props}

	>

		{children}

	

);



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.';



// Other text properties are allowed as well

render(

	

		{text}

	

);

```



#### transform(outputLine, index)



Type: `Function`



Function which transforms children output.

It accepts children and must return transformed children too.



##### children



Type: `string`



Output of child components.



##### index



Type: `number`



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



## Hooks



### useInput(inputHandler, options?)



This hook is used for handling user input.

It's a more convenient alternative to using `useStdin` and listening to `data` events.

The callback you pass to `useInput` is called for each character when user enters any input.

However, if 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 user presses 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 Page Up or Page Down key was pressed, the corresponding property will be `true`.

For example, if user presses Page Down, `key.pageDown` equals `true`.



###### key.meta



Type: `boolean`\

Default: `false`



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



#### 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.



### useApp()



`useApp` is a React hook, which exposes a method to manually exit the app (unmount).



#### exit(error?)



Type: `Function`



Exit (unmount) the whole Ink app.



##### error



Type: `Error`



Optional error. If passed, [`waitUntilExit`](waituntilexit) will reject with that error.



```js

import {useApp} from 'ink';



const Example = () => {

	const {exit} = useApp();



	// Exit the app after 5 seconds

	useEffect(() => {

		setTimeout(() => {

			exit();

		}, 5000);

	}, []);



	return …

};

```



### useStdin()



`useStdin` is a React hook, which exposes stdin stream.



#### stdin



Type: `stream.Readable`\

Default: `process.stdin`



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 ? (

		

	) : (

		

	);

};

```



#### 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 Ctrl+C, 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()



`useStdout` is a React hook, which exposes stdout stream, where Ink renders your app.



#### 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 some external information outside of Ink's rendering and ensure there's no conflict between the two.

It's similar to ``, 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).



### useStderr()



`useStderr` is a React hook, which exposes stderr stream.



#### 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 some external information outside of Ink's rendering and ensure there's no conflict between the two.

It's similar to ``, 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 …

};

```



### useFocus(options?)



Component that uses `useFocus` hook becomes "focusable" to Ink, so when user presses Tab, Ink will switch focus to this component.

If there are multiple components that execute `useFocus` hook, focus will be given to them in the order that these components are rendered in.

This hook returns an object with `isFocused` boolean property, which determines if this component is focused or not.



#### 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 {isFocused ? 'I am focused' : 'I am not focused'};

};



render();

```



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()



This hook exposes methods to enable or disable focus management for all components or manually switch focus to next or previous 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.

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 active component is the last in the list of focusable components, focus will be switched to the first active component.



**Note:** Ink calls this method when user presses Tab.



```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 active component is the first in the list of focusable components, focus will be switched to the last component.



**Note:** Ink calls this method when user presses Shift+Tab.



```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 will be given to the next focusable component.



```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 …

};

```



## API



#### render(tree, options?)



Returns: [`Instance`](#instance)



Mount a component and render the output.



##### tree



Type: `ReactElement`



##### options



Type: `object`



###### stdout



Type: `stream.Writable`\

Default: `process.stdout`



Output stream where app will be rendered.



###### stdin



Type: `stream.Readable`\

Default: `process.stdin`



Input stream where app will listen for input.



###### exitOnCtrlC



Type: `boolean`\

Default: `true`



Configure whether Ink should listen to 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 process is expected to handle it manually.



###### patchConsole



Type: `boolean`\

Default: `true`



Patch console methods to ensure console output doesn't mix with Ink output.

When any of `console.*` methods are called (like `console.log()`), Ink intercepts their output, clears main output, renders output from the console method and then rerenders main output again.

That way both are visible and are not overlapping each other.



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 it.



###### debug



Type: `boolean`\

Default: `false`



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



#### Instance



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



##### rerender(tree)



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



###### tree



Type: `ReactElement`



```jsx

// Update props of the root node

const {rerender} = render();

rerender();



// Replace root node

const {rerender} = render();

rerender();

```



##### unmount()



Manually unmount the whole Ink app.



```jsx

const {unmount} = render();

unmount();

```



##### waitUntilExit()



Returns a promise, which resolves when app is unmounted.



```jsx

const {unmount, waitUntilExit} = render();



setTimeout(unmount, 1000);



await waitUntilExit(); // resolves after `unmount()` is called

```



##### clear()



Clear output.



```jsx

const {clear} = render();

clear();

```



#### measureElement(ref)



Measure the dimensions of a particular `` element.

It returns an object with `width` and `height` properties.

This function is useful when your component needs to know the amount of available space it has. You could use it when you need to change the layout based on the length of its content.



**Note:** `measureElement()` returns correct results only after the initial render, when layout has been calculated. Until then, `width` and `height` equal to zero. It's recommended to call `measureElement()` in a `useEffect` hook, which fires after the component has rendered.



##### ref



Type: `MutableRef`



A reference to a `` element captured with a `ref` property.

See [Refs](https://reactjs.org/docs/refs-and-the-dom.html) for more information on how to capture references.



```jsx

import {render, measureElement, Box, Text} from 'ink';



const Example = () => {

	const ref = useRef();



	useEffect(() => {

		const {width, height} = measureElement(ref.current);

		// width = 100, height = 1

	}, []);



	return (

		

			

				This box will stretch to 100 width

			

		

	);

};



render();

```



## Testing



Ink components are simple to test with [ink-testing-library](https://github.com/vadimdemedes/ink-testing-library).

Here's a simple example that checks how component is rendered:



```jsx

import React from 'react';

import {Text} from 'ink';

import {render} from 'ink-testing-library';



const Test = () => Hello World;

const {lastFrame} = render();



lastFrame() === 'Hello World'; //=> true

```



Check out [ink-testing-library](https://github.com/vadimdemedes/ink-testing-library) for more examples and full documentation.



## Using React Devtools



![](media/devtools.jpg)



Ink supports [React Devtools](https://github.com/facebook/react/tree/master/packages/react-devtools) out-of-the-box. To enable integration with React Devtools in your Ink-based CLI, first ensure you have installed the optional `react-devtools-core` dependency, and then run your app with `DEV=true` environment variable:



```sh

DEV=true my-cli

```



Then, start React Devtools itself:



```sh

npx react-devtools

```



After it starts up, you should see the component tree of your CLI.

You can even inspect and change the props of components, and see the results immediatelly in the CLI, without restarting it.



**Note**: You must manually quit your CLI via Ctrl+C after you're done testing.



## Useful Components



- [ink-text-input](https://github.com/vadimdemedes/ink-text-input) - Text input.

- [ink-spinner](https://github.com/vadimdemedes/ink-spinner) - Spinner.

- [ink-select-input](https://github.com/vadimdemedes/ink-select-input) - Select (dropdown) input.

- [ink-link](https://github.com/sindresorhus/ink-link) - Link.

- [ink-gradient](https://github.com/sindresorhus/ink-gradient) - Gradient color.

- [ink-big-text](https://github.com/sindresorhus/ink-big-text) - Awesome text.

- [ink-image](https://github.com/kevva/ink-image) - Display images inside the terminal.

- [ink-tab](https://github.com/jdeniau/ink-tab) - Tab.

- [ink-color-pipe](https://github.com/LitoMore/ink-color-pipe) - Create color text with simpler style strings.

- [ink-multi-select](https://github.com/karaggeorge/ink-multi-select) - Select one or more values from a list

- [ink-divider](https://github.com/JureSotosek/ink-divider) - A divider.

- [ink-progress-bar](https://github.com/brigand/ink-progress-bar) - Progress bar.

- [ink-table](https://github.com/maticzav/ink-table) - Table.

- [ink-ascii](https://github.com/hexrcs/ink-ascii) - Awesome text component with more font choices, based on Figlet.

- [ink-markdown](https://github.com/cameronhunter/ink-markdown) - Render syntax highlighted Markdown.

- [ink-quicksearch-input](https://github.com/Eximchain/ink-quicksearch-input) - Select component with fast quicksearch-like navigation.

- [ink-confirm-input](https://github.com/kevva/ink-confirm-input) - Yes/No confirmation input.

- [ink-syntax-highlight](https://github.com/vsashyn/ink-syntax-highlight) - Code syntax highlighting.

- [ink-form](https://github.com/lukasbach/ink-form) - Form.

- [ink-task-list](https://github.com/privatenumber/ink-task-list) - Task list.



## Useful Hooks



- [ink-use-stdout-dimensions](https://github.com/cameronhunter/ink-monorepo/tree/master/packages/ink-use-stdout-dimensions) - Subscribe to stdout dimensions.



## Examples



The [`examples`](/examples) directory contains a set of real examples. You can run them with:



```bash

npm run example examples/[example name]

# e.g. npm run example examples/borders

```



- [Jest](examples/jest/jest.tsx) - Implementation of basic Jest UI [(live demo)](https://ink-jest-demo.vadimdemedes.repl.run/).

- [Counter](examples/counter/counter.tsx) - Simple counter that increments every 100ms [(live demo)](https://ink-counter-demo.vadimdemedes.repl.run/).

- [Form with validation](https://github.com/final-form/rff-cli-example) - Manage form state using [Final Form](https://github.com/final-form/final-form#-final-form).

- [Borders](examples/borders/borders.tsx) - Add borders to `` component.

- [Suspense](examples/suspense/suspense.tsx) - Use React Suspense.

- [Table](examples/table/table.tsx) - Render a table with multiple columns and rows.

- [Focus management](examples/use-focus/use-focus.tsx) - Use `useFocus` hook to manage focus between components.

- [User input](examples/use-input/use-input.tsx) - Listen to user input.

- [Write to stdout](examples/use-stdout/use-stdout.tsx) - Write to stdout bypassing main Ink output.

- [Write to stderr](examples/use-stderr/use-stderr.tsx) - Write to stderr bypassing main Ink output.

- [Static](examples/static/static.tsx) - Use `` to render permanent output.

- [Child process](examples/subprocess-output) - Render output from a child process.



## Maintainers



- [Vadim Demedes](https://github.com/vadimdemedes)

- [Sindre Sorhus](https://github.com/sindresorhus)