chalk 6.x

Complete instructions

Verified against chalk@6.0.0 on 2026-09-08. 6 of 6 examples executed.

chalk@^6.0.0

Runtime and package shape

• Chalk 6 is ESM-only and requires Node.js 22 or newer.
• Import the default export or named exports from chalk. Do not use require() or assume a CommonJS entry point.
• Chalk formats strings; it is not a command-line runner. Direct scripts can use its formatting API, while command-line usage belongs to the separate chalk-cli package.

import assert from 'node:assert/strict';
import chalk, {Chalk} from 'chalk';

assert.equal(typeof chalk, 'function');
assert.equal(typeof Chalk, 'function');

const plain = new Chalk({level: 0});
assert.equal(plain.blue('hello'), 'hello');
assert.equal(plain.bold.red('error'), 'error');

Chaining styles and arguments

A style chain is callable: chalk.<style>[.<style>...](text, ...moreText). Multiple arguments are separated by spaces. A chain can be saved and reused because the chain itself is callable.

import assert from 'node:assert/strict';
import {Chalk} from 'chalk';

const color = new Chalk({level: 3});

const error = color.bold.red;
const warning = color.hex('#FFA500');

assert.equal(error('Error!'), '\u001b[1m\u001b[31mError!\u001b[39m\u001b[22m');
assert.equal(warning('Warning!'), '\u001b[38;2;255;165;0mWarning!\u001b[39m');
assert.equal(color.red('Hello', color.underline.bgBlue('world') + '!'), '\u001b[31mHello \u001b[4m\u001b[44mworld\u001b[49m\u001b[24m!\u001b[39m');
assert.equal(color.rgb(123, 45, 67).underline('Underlined reddish color'), '\u001b[38;2;123;45;67m\u001b[4mUnderlined reddish color\u001b[24m\u001b[39m');

Color levels and Chalk

Use new Chalk({level}) when output must be deterministic. Levels are 0 through 3; level 0 disables styling and level 3 enables truecolor. A Chalk instance is callable and its .level can be changed later.

Do not rely on the default instance's detected level in tests or examples: it depends on the environment. Numeric FORCE_COLOR selects that exact level; FORCE_COLOR=true enables color while retaining detection.

import assert from 'node:assert/strict';
import {Chalk} from 'chalk';

const customChalk = new Chalk({level: 0});
assert.equal(customChalk.red('not red'), 'not red');

customChalk.level = 3;
const truecolor = customChalk.rgb(15, 100, 204)('Truecolor');
assert.notEqual(truecolor, 'Truecolor');
assert.ok(truecolor.includes('15;100;204'));

v6 underline styles and underline colors

Version 6 adds underlineDouble, underlineCurly, underlineDotted, and underlineDashed. Underline colors use methods such as underlineHex, underlineRgb, and underlineAnsi256; an underline style must also be applied. There is no basic 16-color underline form.

import assert from 'node:assert/strict';
import {Chalk} from 'chalk';

const color = new Chalk({level: 3});

const typo = color.underlineHex('#DEADED').underlineCurly('typo');
const notice = color.underlineRgb(15, 100, 204).underlineDouble('Hello!');
const dotted = color.underlineDotted('dotted');
const dashed = color.underlineDashed('dashed');

for (const value of [typo, notice, dotted, dashed]) {
  assert.notEqual(value, value.replace(/\u001b\[[0-9;]*m/g, ''));
}
assert.ok(typo.includes('222;173;237'));
assert.ok(notice.includes('15;100;204'));

Color models

The documented color-model methods include rgb, hex, and ansi256, with background equivalents bgRgb, bgHex, and bgAnsi256, and underline equivalents underlineRgb, underlineHex, and underlineAnsi256. At level 1, ansi256() and bgAnsi256() are downsampled to the 16-color range.

import assert from 'node:assert/strict';
import {Chalk} from 'chalk';

const color = new Chalk({level: 3});

assert.ok(color.rgb(1, 2, 3)('x').includes('1;2;3'));
assert.ok(color.hex('#010203')('x').includes('1;2;3'));
assert.ok(color.ansi256(100)('x').includes('38;5;100'));
assert.ok(color.bgRgb(1, 2, 3)('x').includes('48;2;1;2;3'));
assert.ok(color.bgHex('#010203')('x').includes('48;2;1;2;3'));
assert.ok(color.bgAnsi256(100)('x').includes('48;5;100'));
assert.ok(color.underlineRgb(1, 2, 3).underline('x').includes('58;2;1;2;3'));
assert.ok(color.underlineHex('#010203').underline('x').includes('58;2;1;2;3'));
assert.ok(color.underlineAnsi256(100).underline('x').includes('58;5;100'));

Named exports and stderr instance

The package exports chalkStderr, a separate instance configured using stderr color support, plus supportsColor and supportsColorStderr. It also exports style-name arrays:

• modifierNames
• foregroundColorNames
• backgroundColorNames
• underlineColorNames
• colorNames

Aliases include modifiers, foregroundColors, backgroundColors, and colors.

import assert from 'node:assert/strict';
import {
  chalkStderr,
  modifierNames,
  foregroundColorNames,
  backgroundColorNames,
  underlineColorNames,
  colorNames,
  modifiers,
  foregroundColors,
  backgroundColors,
  colors,
  supportsColor,
  supportsColorStderr,
} from 'chalk';

assert.equal(typeof chalkStderr, 'function');
assert.ok(modifierNames.includes('bold'));
assert.ok(foregroundColorNames.includes('red'));
assert.ok(Array.isArray(backgroundColorNames));
assert.ok(Array.isArray(underlineColorNames));
assert.ok(Array.isArray(colorNames));
assert.equal(modifiers, modifierNames);
assert.equal(foregroundColors, foregroundColorNames);
assert.equal(backgroundColors, backgroundColorNames);
assert.equal(colors, colorNames);
assert.ok(typeof supportsColor === 'boolean' || typeof supportsColor === 'object');
assert.ok(typeof supportsColorStderr === 'boolean' || typeof supportsColorStderr === 'object');
assert.notEqual(chalkStderr, undefined);

Common mistakes

• Do not copy a CommonJS require('chalk') shape from older examples; Chalk 6 is ESM-only.
• Do not assume the older package metadata or older Node.js support applies. Chalk 6 requires Node.js 22+.
• Do not test the default chalk output as colored without controlling the color level; terminal/environment detection may disable color.
• Do not treat underlineHex, underlineRgb, or underlineAnsi256 as complete underline styles by themselves. Combine them with an underline style such as underline, underlineCurly, or underlineDouble.
• Do not expect a basic 16-color underline API; underline colors are exposed through the color-model methods.
• Do not assume that every intuitive color name is present in foregroundColorNames; use the exported arrays to discover supported names rather than asserting an unsupported name such as pink.
• Do not assume ansi256() always emits a 256-color sequence: at level 1 it is downsampled to 16 colors.
• Do not use describe, it, or expect in a directly executed script. Chalk does not provide test-runner globals.
• Do not use Chalk as the CLI executable. The separately documented chalk-cli package provides command-line behavior.

Not covered

This skill does not cover Chalk's complete style-name list or every escape-sequence detail, terminal-specific color detection behavior, invalid color argument handling, TypeScript compiler configuration, or chalk-cli command syntax. It also does not cover framework or test-runner integration.