chalk

What is chalk?

The chalk npm package is a popular library for styling and coloring text in the terminal. It provides an easy-to-use API for applying various text styles, such as color, background color, bold, underline, and more, to console output in Node.js applications.

What are chalk's main functionalities?

Text color

Change the color of the text. In this example, the text 'Hello world!' will be printed in blue.

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

Background color

Change the background color of the text. Here, 'Hello world!' will have a red background.

console.log(chalk.bgRed('Hello world!'));

Text styles

Apply text styles such as bold, italic, underline, etc. This code sample makes the text 'Hello world!' bold.

console.log(chalk.bold('Hello world!'));

Combining styles

Combine multiple styles together. The text 'Hello world!' will be bold with blue text and a red background.

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

Composing multiple styles

Create reusable composed style functions. This creates an 'error' style that is bold and red, which can be used to print error messages.

const error = chalk.bold.red; console.log(error('Error!'));

Template literals

Use tagged template literals for styling. This allows for more readable code when applying multiple styles.

console.log(chalk`{blue.bold Hello} {red world!}`);

Other packages similar to chalk

colors

The 'colors' package is similar to chalk and allows for coloring and styling terminal output. Unlike chalk, 'colors' extends String.prototype to add color and style methods directly to strings, which some may find less clean than chalk's functional approach.

cli-color

The 'cli-color' package provides similar functionality to chalk with a focus on performance. It offers a chainable API and additional features like column alignment and line width control, but it might be more complex to use than chalk.

ansi-styles

The 'ansi-styles' package is a lower-level library that chalk itself uses. It provides ANSI escape codes for styling text in the terminal. It's more manual and less user-friendly than chalk but offers more control for those who need it.

ink

While 'ink' is not a direct alternative to chalk, it is a React-based rendering library for interactive command-line apps that includes its own system for styling text. It's more powerful for building full CLI applications but is overkill for simple text styling.

README

Terminal string styling done right

colors.js is currently the most popular string styling module, but it has serious deficiencies like extending String.prototype which causes all kinds of problems. Although there are other ones, they either do too much or not enough.

Chalk is a clean and focused alternative.

Why

• Highly performant
• Doesn't extend String.prototype
• Expressive API
• Ability to nest styles
• Clean and focused
• Auto-detects color support
• Actively maintained
• Used by 1000+ modules

Install

$ npm install --save chalk

Usage

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

var chalk = require('chalk');

// style a string
console.log(  chalk.blue('Hello world!')  );

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

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

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

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

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

Easily define your own themes.

var chalk = require('chalk');
var error = chalk.bold.red;
console.log(error('Error!'));

Take advantage of console.log string substitution.

var 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.

Multiple arguments will be separated by space.

chalk.enabled

Color support is automatically detected, but you can override it.

chalk.supportsColor

Detect whether the terminal supports color.

Can be overridden by the user with the flags --color and --no-color.

Used internally and handled for you, but exposed for convenience.

chalk.styles

Exposes the styles as ANSI escape codes.

Generally not useful, but you might need just the .open or .close escape code if you're mixing externally styled strings with yours.

var chalk = require('chalk');

console.log(chalk.styles.red);
//=> {open: '\u001b[31m', close: '\u001b[39m'}

console.log(chalk.styles.red.open + 'Hello' + chalk.styles.red.close);

chalk.hasColor(string)

Check whether a string has color.

chalk.stripColor(string)

Strip color from a string.

Can be useful in combination with .supportsColor to strip color on externally styled text when it's not supported.

Example:

var chalk = require('chalk');
var styledString = getText();

if (!chalk.supportsColor) {
	styledString = chalk.stripColor(styledString);
}

Styles

General

• reset
• bold
• dim
• italic (not widely supported)
• underline
• inverse
• hidden
• strikethrough (not widely supported)

Text colors

• black
• red
• green
• yellow
• blue
• magenta
• cyan
• white
• gray

Background colors

• bgBlack
• bgRed
• bgGreen
• bgYellow
• bgBlue
• bgMagenta
• bgCyan
• bgWhite

License

MIT © Sindre Sorhus