Terminal string styling done right

<a href="https://github.com/chalk/chalk/releases/tag/v2.0.0">See what's new in Chalk 2</a>

Highlights

Expressive API
Highly performant
Ability to nest styles
256/Truecolor color support
Auto-detects color support
Doesn't extend String.prototype
Clean and focused
Actively maintained
Used by ~23,000 packages as of December 31, 2017

Install

$ npm install chalk

Usage

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.

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:

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:

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

API

chalk.<tt><style>[.<style>...](string, [string...])</tt>

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

Chain 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 explicitly disabled via the constructor or chalk.level is 0.

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

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:

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

Levels are as follows:

0. All colors disabled

Basic color support (16 colors)
256 color support
Truecolor support (16 million colors)

chalk.supportsColor

Detect whether the terminal 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)*
visible (Text is emitted only if enabled)

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.

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:

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 (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 - 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.hsv(32, 100, 100).bold('Orange!')
[hwb](https://en.wikipedia.org/wiki/HWB_color_model) - Example:chalk.hwb(32, 0, 50).bold('Orange!') -ansi16 -ansi256`

Windows

If you're on Windows, do yourself a favor and use cmder instead of cmd.exe.

Origin story

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 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.

chalk-cli - CLI for this module
ansi-styles - ANSI escape codes for styling strings in the terminal
supports-color - Detect whether a terminal supports color
strip-ansi - Strip ANSI escape codes
strip-ansi-stream - Strip ANSI escape codes from a stream
has-ansi - Check if a string has ANSI escape codes
ansi-regex - Regular expression for matching ANSI escape codes
wrap-ansi - Wordwrap a string with ANSI escape codes
slice-ansi - Slice a string with ANSI escape codes
color-convert - Converts colors between different models
chalk-animation - Animate strings in the terminal
gradient-string - Apply color gradients to strings
chalk-pipe - Create chalk style schemes with simpler style strings
terminal-link - Create clickable links in the terminal

Maintainers

License

MIT