React for CLIs. Build and test your CLI output using components.
Install
$ npm install ink@next
Usage
import React, {Component} from 'react';
import {render, Color} from 'ink';
class Counter extends Component {
constructor() {
super();
this.state = {
i: 0
};
}
render() {
return (
<Color green>
{this.state.i} tests passed
</Color>
);
}
componentDidMount() {
this.timer = setInterval(() => {
this.setState({
i: this.state.i + 1
});
}, 100);
}
componentWillUnmount() {
clearInterval(this.timer);
}
}
render(<Counter/>);
Useful Components
Built with Ink
- emoj - Find relevant emoji on the command-line.
- emma - Terminal assistant to find and install npm packages.
Guide
Ink's goal is to provide the same component-based UI building experience that React provides, but for command-line apps. It uses yoga-layout to allow Flexbox layouts in the terminal. If you are already familiar with React, you already know Ink.
The key difference you have to remember is that the rendering result isn't a DOM, but a string, which Ink writes to the output.
Getting Started
To ensure all examples work and you can begin your adventure with Ink, make sure to set up Babel with a React preset. After installing Babel, configure it in package.json
:
{
"babel": {
"presets": [
"@babel/preset-react"
]
}
}
Don't forget to import React
into every file that contains JSX:
import React from 'react';
import {Box} from 'ink';
const Demo = () => <Box/>;
To get started, quickly scaffold out a project using Ink CLI Yeoman generator. To create a new component that you intend to publish, you can use Ink Component generator.
API
Since Ink is a React renderer, it means that all of React is supported.
Head over to React website for documentation on how to use it.
In this readme only Ink's methods will be documented.
render(tree, options)
Mount a component and render the output.
tree
Type: ReactElement
options
stdout
Type: Stream
Default: process.stdout
Output stream where app will be rendered.
stdin
Type: Stream
Default: process.stdin
Input stream where app will listen for input.
debug
Type: Boolean
Default: false
If true
, each update will be rendered as a separate output, without replacing the previous one.
import React, {Component} from 'react';
import {render, Box} from 'ink';
class Counter extends Component {
constructor() {
super();
this.state = {
i: 0
};
}
render() {
return (
<Box>
Iteration #{this.state.i}
</Box>
);
}
componentDidMount() {
this.timer = setInterval(() => {
this.setState(prevState => ({
i: prevState.i + 1
}));
}, 100);
}
componentWillUnmount() {
clearInterval(this.timer);
}
}
const unmount = render(<Counter/>);
setTimeout(() => {
unmount();
}, 1000);
There's also a shortcut to avoid passing options
object:
render(<Counter>, process.stdout);
Building Layouts
Ink uses Yoga - a Flexbox layout engine to build great user interfaces for your CLIs.
It's important to remember that each element is a Flexbox container.
Think of it as if each <div>
in the browser had display: flex
.
See <Box>
built-in component below for documentation on how to use Flexbox layouts in Ink.
Built-in Components
<Box>
<Box>
it's an essential Ink component to build your layout. It's like a <div>
in a browser.
Import:
import {Box} from 'ink';
Padding
paddingTop
Type: number
Default: 0
paddingBottom
Type: number
Default: 0
paddingLeft
Type: number
Default: 0
paddingRight
Type: number
Default: 0
paddingX
Type: number
Default: 0
paddingY
Type: number
Default: 0
padding
Type: number
Default: 0
<Box paddingTop={2}>Top</Box>
<Box paddingBottom={2}>Bottom</Box>
<Box paddingLeft={2}>Left</Box>
<Box paddingRight={2}>Right</Box>
<Box paddingX={2}>Left and right</Box>
<Box paddingY={2}>Top and bottom</Box>
<Box padding={2}>Top, bottom, left and right</Box>
Margin
marginTop
Type: number
Default: 0
marginBottom
Type: number
Default: 0
marginLeft
Type: number
Default: 0
marginRight
Type: number
Default: 0
marginX
Type: number
Default: 0
marginY
Type: number
Default: 0
margin
Type: number
Default: 0
<Box marginTop={2}>Top</Box>
<Box marginBottom={2}>Bottom</Box>
<Box marginLeft={2}>Left</Box>
<Box marginRight={2}>Right</Box>
<Box marginX={2}>Left and right</Box>
<Box marginY={2}>Top and bottom</Box>
<Box margin={2}>Top, bottom, left and right</Box>
Flex
flexGrow
Type: number
See flex-grow.
<Box>
Label:
<Box flexGrow={1}>
Fills all remaining space
</Box>
</Box>
flexShrink
Type: number
See flex-shrink.
<Box width={20}>
<Box flexShrink={2} width={10}>
Will be 1/4
</Box>
<Box width={10}>
Will be 3/4
</Box>
</Box>
flexDirection
Type: string
Allowed values: row
, row-reverse
, column
and column-reverse
See flex-direction.
<Box>
<Box marginRight={1}>X</Box>
<Box>Y</Box>
</Box>
<Box flexDirection="row-reverse">
<Box>X</Box>
<Box marginRight={1}>Y</Box>
</Box>
<Box flexDirection="column">
<Box>X</Box>
<Box>Y</Box>
</Box>
<Box flexDirection="column-reverse">
<Box>X</Box>
<Box>Y</Box>
</Box>
alignItems
Type: string
Allowed values: flex-start
, center
and flex-end
See align-items.
<Box alignItems="flex-start">
<Box marginRight={1}>X</Box>
<Box>{`A\nB\nC`}</Box>
</Box>
<Box alignItems="center">
<Box marginRight={1}>X</Box>
<Box>{`A\nB\nC`}</Box>
</Box>
<Box alignItems="flex-end">
<Box marginRight={1}>X</Box>
<Box>{`A\nB\nC`}</Box>
</Box>
justifyContent
Type: string
Allowed values: flex-start
, center
, flex-end
, space-between
and space-around
.
See justify-content.
<Box justifyContent="flex-start">
<Box>X</Box>
</Box>
<Box justifyContent="center">
<Box>X</Box>
</Box>
<Box justifyContent="flex-end">
<Box>X</Box>
</Box>
<Box justifyContent="space-between">
<Box>X</Box>
<Box>Y</Box>
</Box>
<Box justifyContent="space-around">
<Box>X</Box>
<Box>Y</Box>
</Box>
<Color>
The <Color>
compoment is a simple wrapper around the chalk
API.
It supports all of the chalk's methods as props
.
Import:
import {Color} from 'ink';
Usage:
<Color rgb={[255, 255, 255]} bgKeyword="magenta">
Hello!
</Color>
<Color hex="#000000" bgHex="#FFFFFF">
Hey there
</Color>
<Color blue>
I'm blue
</Color>
<Text>
This component can change the style of the text, make it bold, underline, italic or strikethrough.
Import:
import {Text} from 'ink';
bold
Type: boolean
Default: false
italic
Type: boolean
Default: false
underline
Type: boolean
Default: false
strikethrough
Type: boolean
Default: false
Usage:
<Text bold>I am bold</Text>
<Text italic>I am italic</Text>
<Text underline>I am underline</Text>
<Text strikethrough>I am strikethrough</Text>
<Static>
<Static>
component allows permanently rendering output to stdout and preserving it across renders.
Components passed to <Static>
as children will be written to stdout only once and will never be rerendered.
<Static>
output comes first, before any other output from your components, no matter where it is in the tree.
In order for this mechanism to work properly, at most one <Static>
component must be present in your node tree and components that were rendered must never update their output. Ink will detect new children appended to <Static>
and render them to stdout.
Note: <Static>
accepts only an array of children and each of them must have a unique key.
Example use case for this component is Jest's output:
Jest continuosuly writes the list of completed tests to the output, while updating test results at the bottom of the output in real-time. Here's how this user interface could be implemented with Ink:
<Fragment>
<Static>
{tests.map(test => (
<Test key={test.id} title={test.title}/>
))}
</Static>
<Box marginTop={1}>
<TestResults passed={results.passed} failed={results.failed}/>
</Box>
</Fragment>
See examples/jest for a basic implementation of Jest's UI.
<StdinContext>
<StdinContext>
is a React context, which exposes several props.
Import:
import {StdinContext} from 'ink';
stdin
Type: Stream
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.
Usage:
<StdinContext.Consumer>
{({ stdin }) => (
<MyComponent stdin={stdin}/>
)}
</StdinContext.Consumer>
setRawMode
Type: function
See setRawMode.
Ink exposes this function via own <StdinContext>
to be able to handle Ctrl+C, that's why you should use Ink's setRawMode
instead of process.stdin.setRawMode
.
Usage:
<StdinContext.Consumer>
{({ setRawMode }) => (
<MyComponent setRawMode={setRawMode}/>
)}
</StdinContext.Consumer>
<StdoutContext>
<StdoutContext>
is a React context, which exposes stdout stream, where Ink renders your app.
Import:
import {StdoutContext} from 'ink';
stdout
Type: Stream
Default: process.stdout
Usage:
<StdoutContext.Consumer>
{({ stdout }) => (
<MyComponent stdout={stdout}/>
)}
</StdoutContext.Consumer>
License
MIT © Vadim Demedes