chalk/readme.md

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> Terminal string styling done right

[![Build Status](https://travis-ci.org/chalk/chalk.svg?branch=master)](https://travis-ci.org/chalk/chalk) [![Coverage Status](https://coveralls.io/repos/github/chalk/chalk/badge.svg?branch=master)](https://coveralls.io/github/chalk/chalk?branch=master) [![](https://img.shields.io/badge/unicorn-approved-ff69b4.svg)](https://www.youtube.com/watch?v=9auOCbH5Ns4) [![XO code style](https://img.shields.io/badge/code_style-XO-5ed9c7.svg)](https://github.com/sindresorhus/xo)

### [See what's new in Chalk 2](https://github.com/chalk/chalk/releases/tag/v2.0.0)

![](https://github.com/chalk/ansi-styles/raw/master/screenshot.png)


## Highlights

- Expressive API
- Highly performant
- Ability to nest styles
- [256/Truecolor color support](#256-and-truecolor-color-support)
- Auto-detects color support
- Doesn't extend `String.prototype`
- Clean and focused
- Actively maintained
- [Used by ~17,000 packages](https://www.npmjs.com/browse/depended/chalk) as of June 20th, 2017


## Install

```console
$ npm install chalk
```


## Usage

```js
const chalk = require('chalk');

console.log(chalk.blue('Hello world!'));
```

Chalk comes with an easy to use composable API where you just chain and nest the styles you want.

```js
const chalk = require('chalk');
const log = console.log;

// Combine styled and normal strings
log(chalk.blue('Hello') + 'World' + chalk.red('!'));

// Compose multiple styles using the chainable API
log(chalk.blue.bgRed.bold('Hello world!'));

// Pass in multiple arguments
log(chalk.blue('Hello', 'World!', 'Foo', 'bar', 'biz', 'baz'));

// Nest styles
log(chalk.red('Hello', chalk.underline.bgBlue('world') + '!'));

// Nest styles of the same type even (color, underline, background)
log(chalk.green(
	'I am a green line ' +
	chalk.blue.underline.bold('with a blue substring') +
	' that becomes green again!'
));

// ES2015 template literal
log(`
CPU: ${chalk.red('90%')}
RAM: ${chalk.green('40%')}
DISK: ${chalk.yellow('70%')}
`);

// ES2015 tagged template literal
log(chalk`
CPU: {red ${cpu.totalPercent}%}
RAM: {green ${ram.used / ram.total * 100}%}
DISK: {rgb(255,131,0) ${disk.used / disk.total * 100}%}
`);

// Use RGB colors in terminal emulators that support it.
log(chalk.keyword('orange')('Yay for orange colored text!'));
log(chalk.rgb(123, 45, 67).underline('Underlined reddish color'));
log(chalk.hex('#DEADED').bold('Bold gray!'));
```

Easily define your own themes:

```js
const chalk = require('chalk');

const error = chalk.bold.red;
const warning = chalk.keyword('orange');

console.log(error('Error!'));
console.log(warning('Warning!'));
```

Take advantage of console.log [string substitution](https://nodejs.org/docs/latest/api/console.html#console_console_log_data_args):

```js
const name = 'Sindre';
console.log(chalk.green('Hello %s'), name);
//=> 'Hello Sindre'
```


## API

### chalk.`<style>[.<style>...](string, [string...])`

Example: `chalk.red.bold.underline('Hello', 'world');`

Chain [styles](#styles) and call the last one as a method with a string argument. Order doesn't matter, and later styles take precedent in case of a conflict. This simply means that `chalk.red.yellow.green` is equivalent to `chalk.green`.

Multiple arguments will be separated by space.

### chalk.enabled

Color support is automatically detected, as is the level (see `chalk.level`). However, if you'd like to simply enable/disable Chalk, you can do so via the `.enabled` property.

Chalk is enabled by default unless expicitly disabled via the constructor or `chalk.level` is `0`.

If you need to change this in a reusable module, create a new instance:

```js
const ctx = new chalk.constructor({enabled: false});
```

### chalk.level

Color support is automatically detected, but you can override it by setting the `level` property. You should however only do this in your own code as it applies globally to all Chalk consumers.

If you need to change this in a reusable module, create a new instance:

```js
const ctx = new chalk.constructor({level: 0});
```

Levels are as follows:

0. All colors disabled
1. Basic color support (16 colors)
2. 256 color support
3. Truecolor support (16 million colors)

### chalk.supportsColor

Detect whether the terminal [supports color](https://github.com/chalk/supports-color). Used internally and handled for you, but exposed for convenience.

Can be overridden by the user with the flags `--color` and `--no-color`. For situations where using `--color` is not possible, add the environment variable `FORCE_COLOR=1` to forcefully enable color or `FORCE_COLOR=0` to forcefully disable. The use of `FORCE_COLOR` overrides all other color support checks.

Explicit 256/Truecolor mode can be enabled using the `--color=256` and `--color=16m` flags, respectively.


## Styles

### Modifiers

- `reset`
- `bold`
- `dim`
- `italic` *(Not widely supported)*
- `underline`
- `inverse`
- `hidden`
- `strikethrough` *(Not widely supported)*

### Colors

- `black`
- `red`
- `green`
- `yellow`
- `blue` *(On Windows the bright version is used since normal blue is illegible)*
- `magenta`
- `cyan`
- `white`
- `gray` ("bright black")
- `redBright`
- `greenBright`
- `yellowBright`
- `blueBright`
- `magentaBright`
- `cyanBright`
- `whiteBright`

### Background colors

- `bgBlack`
- `bgRed`
- `bgGreen`
- `bgYellow`
- `bgBlue`
- `bgMagenta`
- `bgCyan`
- `bgWhite`
- `bgBlackBright`
- `bgRedBright`
- `bgGreenBright`
- `bgYellowBright`
- `bgBlueBright`
- `bgMagentaBright`
- `bgCyanBright`
- `bgWhiteBright`


## Tagged template literal

Chalk can be used as a [tagged template literal](http://exploringjs.com/es6/ch_template-literals.html#_tagged-template-literals).

```js
const chalk = require('chalk');

const miles = 18;
const calculateFeet = miles => miles * 5280;

console.log(chalk`
  There are {bold 5280 feet} in a mile.
  In {bold ${miles} miles}, there are {green.bold ${calculateFeet(miles)} feet}.
`);
```

Blocks are delimited by an opening curly brace (`{`), a style, some content, and a closing curly brace (`}`).

Template styles are chained exactly like normal Chalk styles. The following two statements are equivalent:

```js
console.log(chalk.bold.rgb(10, 100, 200)('Hello!'));
console.log(chalk`{bold.rgb(10,100,200) Hello!}`);
```

Note that function styles (`rgb()`, `hsl()`, `keyword()`, etc.) may not contain spaces between parameters.

All interpolated values (`` chalk`${foo}` ``) are converted to strings via the `.toString()` method. All curly braces (`{` and `}`) in interpolated value strings are escaped.


## 256 and Truecolor color support

Chalk supports 256 colors and [Truecolor](https://gist.github.com/XVilka/8346728) (16 million colors) on supported terminal apps.

Colors are downsampled from 16 million RGB values to an ANSI color format that is supported by the terminal emulator (or by specifying `{level: n}` as a Chalk option). For example, Chalk configured to run at level 1 (basic color support) will downsample an RGB value of #FF0000 (red) to 31 (ANSI escape for red).

Examples:

- `chalk.hex('#DEADED').underline('Hello, world!')`
- `chalk.keyword('orange')('Some orange text')`
- `chalk.rgb(15, 100, 204).inverse('Hello!')`

Background versions of these models are prefixed with `bg` and the first level of the module capitalized (e.g. `keyword` for foreground colors and `bgKeyword` for background colors).

- `chalk.bgHex('#DEADED').underline('Hello, world!')`
- `chalk.bgKeyword('orange')('Some orange text')`
- `chalk.bgRgb(15, 100, 204).inverse('Hello!')`

The following color models can be used:

- [`rgb`](https://en.wikipedia.org/wiki/RGB_color_model) - Example: `chalk.rgb(255, 136, 0).bold('Orange!')`
- [`hex`](https://en.wikipedia.org/wiki/Web_colors#Hex_triplet) - Example: `chalk.hex('#FF8800').bold('Orange!')`
- [`keyword`](https://www.w3.org/wiki/CSS/Properties/color/keywords) (CSS keywords) - Example: `chalk.keyword('orange').bold('Orange!')`
- [`hsl`](https://en.wikipedia.org/wiki/HSL_and_HSV) - Example: `chalk.hsl(32, 100, 50).bold('Orange!')`
- [`hsv`](https://en.wikipedia.org/wiki/HSL_and_HSV) - Example: `chalk.hsl(32, 1, 1).bold('Orange!')`
- [`hwb`](https://en.wikipedia.org/wiki/HWB_color_model)  - Example: `chalk.hsl(32, 0, 50).bold('Orange!')`
- `ansi16`
- `ansi256`


## Windows

If you're on Windows, do yourself a favor and use [`cmder`](http://cmder.net/) instead of `cmd.exe`.


## Origin story

[colors.js](https://github.com/Marak/colors.js) used to be the most popular string styling module, but it has serious deficiencies like extending `String.prototype` which causes all kinds of [problems](https://github.com/yeoman/yo/issues/68) and the package is unmaintained. Although there are other packages, they either do too much or not enough. Chalk is a clean and focused alternative.


## Related

- [chalk-cli](https://github.com/chalk/chalk-cli) - CLI for this module
- [ansi-styles](https://github.com/chalk/ansi-styles) - ANSI escape codes for styling strings in the terminal
- [supports-color](https://github.com/chalk/supports-color) - Detect whether a terminal supports color
- [strip-ansi](https://github.com/chalk/strip-ansi) - Strip ANSI escape codes
- [strip-ansi-stream](https://github.com/chalk/strip-ansi-stream) - Strip ANSI escape codes from a stream
- [has-ansi](https://github.com/chalk/has-ansi) - Check if a string has ANSI escape codes
- [ansi-regex](https://github.com/chalk/ansi-regex) - Regular expression for matching ANSI escape codes
- [wrap-ansi](https://github.com/chalk/wrap-ansi) - Wordwrap a string with ANSI escape codes
- [slice-ansi](https://github.com/chalk/slice-ansi) - Slice a string with ANSI escape codes
- [color-convert](https://github.com/qix-/color-convert) - Converts colors between different models
- [chalk-animation](https://github.com/bokub/chalk-animation) - Animate strings in the terminal
- [gradient-string](https://github.com/bokub/gradient-string) - Apply color gradients to strings
- [chalk-pipe](https://github.com/LitoMore/chalk-pipe) - Create chalk style schemes with simpler style strings


## Maintainers

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


## License

MIT