` 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, underlined, 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 (make it less bright). ```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` Invert 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 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 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 as a percentage, which will calculate the width based on the width of the 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 as a percentage, which will calculate the height based on the height of the 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. A 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 an 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` `space-evenly` 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 ] 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 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 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. A 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 ``` ##### 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. A 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. #### Background ##### backgroundColor Type: `string` Background color for the element. Accepts the same values as [`color`](#color) in the `` component. ```jsx Red background Orange background Green background ``` The background color fills the entire `` area and is inherited by child `` components unless they specify their own `backgroundColor`. ```jsx Blue inherited Yellow override Blue inherited again ``` Background colors work with borders and padding: ```jsx Background with border and padding ``` See example in [examples/box-backgrounds](examples/box-backgrounds/box-backgrounds.tsx). ### `` 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 space 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" 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 = () => ( Top Bottom ); render(); ``` ### `` `` 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 `` 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 `` 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 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 `` 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) for supported properties. ```jsx {...} ``` #### 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 {(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'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 `` 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, the layout will be incorrect. ```jsx import {render, Transform} from 'ink'; const Example = () => ( output.toUpperCase()}> Hello World ); render(); ``` 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 = ({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 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?) This hook is used for handling 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.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 that 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 that exposes the stdin stream. #### 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 ? ( ) : ( ); }; ``` #### 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 that exposes the 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 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 that exposes the 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 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?) A component that uses the `useFocus` hook becomes "focusable" to Ink, so when the user presses Tab, 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 {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. 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 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 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 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 … }; ``` ### useIsScreenReaderEnabled() 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 ( {isScreenReaderEnabled ? 'Screen reader is enabled' : 'Screen reader is disabled'} ); }; ``` ## 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. ###### 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. 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 a metrics object. ###### 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. #### Instance This is the object that `render()` returns. ##### rerender(tree) Replace the 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 that resolves when the 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. 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 can 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 the layout has been calculated. Until then, `width` and `height` equal 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 the `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 the `DEV=true` environment variable: ```sh DEV=true my-cli ``` Then, start React Devtools itself: ```sh npx react-devtools ``` After it starts, you should see the component tree of your CLI. You can even inspect and change the props of components, and see the results immediately in the CLI, without restarting it. **Note**: You must manually quit your CLI via Ctrl+C after you're done testing. ## Screen Reader Support Ink has basic support for screen readers. To enable it, you can either pass the `isScreenReaderEnabled` option to the `render` function or set the `INK_SCREEN_READER` environment variable to `true`. Ink implements a small subset of functionality from the [ARIA specification](https://developer.mozilla.org/en-US/docs/Web/Accessibility/ARIA). ```jsx render(, {isScreenReaderEnabled: true}); ``` When screen reader support is enabled, Ink will try its best to generate a screen-reader-friendly output. For example, for this code: ```jsx Accept terms and conditions ``` Ink will generate the following output for screen readers: ``` (checked) checkbox: Accept terms and conditions ``` You can also provide a custom label for screen readers if you want to render something different for them. For example, if you are building a progress bar, you can use `aria-label` to provide a more descriptive label for screen readers. ```jsx 50% ``` In the example above, the screen reader will read "Progress: 50%" instead of "50%". ### `aria-label` Type: `string` A label for the element for screen readers. ### `aria-hidden` Type: `boolean`\ Default: `false` Hide the element from screen readers. ##### aria-role Type: `string` The role of the element. Supported values: - `button` - `checkbox` - `radio` - `radiogroup` - `list` - `listitem` - `menu` - `menuitem` - `progressbar` - `tab` - `tablist` - `timer` - `toolbar` - `table` ##### aria-state Type: `object` The state of the element. Supported values: - `checked` (boolean) - `disabled` (boolean) - `expanded` (boolean) - `selected` (boolean) ## Creating Components When building custom components, it's important to keep accessibility in mind. While Ink provides the building blocks, ensuring your components are accessible will make your CLIs usable by a wider audience. ### General Principles - **Provide screen reader-friendly output:** Use the `useIsScreenReaderEnabled` hook to detect if a screen reader is active. You can then render more descriptive output for screen reader users. - **Leverage ARIA props:** For components that have a specific role (e.g., a checkbox or button), use the `aria-role`, `aria-state`, and `aria-label` props on `` and `` to provide semantic meaning to screen readers. For a practical example of building an accessible component, see the [ARIA example](/examples/aria/aria.tsx). ## 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-picture](https://github.com/endernoke/ink-picture) - Display images. - [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. - [ink-spawn](https://github.com/kraenhansen/ink-spawn) - Spawn child processes. - [ink-titled-box](https://github.com/mishieck/ink-titled-box) - Box with a title. - [ink-chart](https://github.com/pppp606/ink-chart) - Sparkline and bar chart. ## 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. - [Counter](examples/counter/counter.tsx) - A simple counter that increments every 100ms. - [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 the `` component. - [Suspense](examples/suspense/suspense.tsx) - Use React Suspense. - [Table](examples/table/table.tsx) - Renders a table with multiple columns and rows. - [Focus management](examples/use-focus/use-focus.tsx) - Use the `useFocus` hook to manage focus between components. - [User input](examples/use-input/use-input.tsx) - Listen for 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 the `` component to render permanent output. - [Child process](examples/subprocess-output) - Renders output from a child process. ## Maintainers - [Vadim Demedes](https://github.com/vadimdemedes) - [Sindre Sorhus](https://github.com/sindresorhus)