` 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` `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 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. - [ink-spawn](https://github.com/kraenhansen/ink-spawn) - Spawn child processes. ## 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)