Terminal string styling done right
See what’s new in Chalk 2¶ ↑
<img src=“cdn.rawgit.com/chalk/ansi-styles/8261697c95bf34b6c7767e2cbe9941a851d59385/screenshot.svg” alt=“” width=“900”>
Highlights¶ ↑
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Expressive API
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Highly performant
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Ability to nest styles
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Auto-detects color support
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Doesn't extend
String.prototype
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Clean and focused
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Actively maintained
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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.<style>[.<style>...](string, [string...])
¶ ↑
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:
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All colors disabled
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Basic color support (16 colors)
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256 color support
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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¶ ↑
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reset
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bold
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dim
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italic
(Not widely supported) -
underline
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inverse
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hidden
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strikethrough
(Not widely supported) -
visible
(Text is emitted only if enabled)
Colors¶ ↑
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black
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red
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green
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yellow
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blue
(On Windows the bright version is used since normal blue is illegible) -
magenta
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cyan
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white
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gray
(“bright black”) -
redBright
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greenBright
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yellowBright
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blueBright
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magentaBright
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cyanBright
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whiteBright
Background colors¶ ↑
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bgBlack
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bgRed
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bgGreen
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bgYellow
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bgBlue
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bgMagenta
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bgCyan
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bgWhite
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bgBlackBright
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bgRedBright
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bgGreenBright
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bgYellowBright
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bgBlueBright
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bgMagentaBright
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bgCyanBright
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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:
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chalk.hex('#DEADED').underline('Hello, world!')
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chalk.keyword('orange')('Some orange text')
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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).
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chalk.bgHex('#DEADED').underline('Hello, world!')
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chalk.bgKeyword('orange')('Some orange text')
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chalk.bgRgb(15, 100, 204).inverse('Hello!')
The following color models can be used:
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{
rgb
} - Example:chalk.rgb(255, 136, 0).bold('Orange!')
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{
hex
} - Example:chalk.hex('#FF8800').bold('Orange!')
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{
keyword
} (CSS keywords) - Example:chalk.keyword('orange').bold('Orange!')
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{
hsl
} - Example:chalk.hsl(32, 100, 50).bold('Orange!')
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{
hsv
} - Example:chalk.hsv(32, 100, 100).bold('Orange!')
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{
hwb
} - Example:chalk.hwb(32, 0, 50).bold('Orange!')
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ansi16
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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.
Related¶ ↑
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chalk-cli - CLI for this module
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ansi-styles - ANSI escape codes for styling strings in the terminal
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supports-color - Detect whether a terminal supports color
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strip-ansi - Strip ANSI escape codes
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strip-ansi-stream - Strip ANSI escape codes from a stream
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has-ansi - Check if a string has ANSI escape codes
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ansi-regex - Regular expression for matching ANSI escape codes
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wrap-ansi - Wordwrap a string with ANSI escape codes
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slice-ansi - Slice a string with ANSI escape codes
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color-convert - Converts colors between different models
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chalk-animation - Animate strings in the terminal
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gradient-string - Apply color gradients to strings
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chalk-pipe - Create chalk style schemes with simpler style strings
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terminal-link - Create clickable links in the terminal
Maintainers¶ ↑
License¶ ↑
MIT