is-valid-css-color

is-valid-css-color

A fast, lightweight validator for modern CSS color strings.

• Broad format coverage: hex, color keywords, rgb(), hsl(), hwb(), lab(), lch(), oklab(), oklch(), and color()
• Legacy + modern syntax: rgb() and hsl() accept both comma-separated legacy and space-separated modern forms, including none channels and /-delimited alpha
• Dual package: ships both ESM and CommonJS builds, use import or require()
• Per-format exports: each validator is individually exported and tree-shakeable, so you only import what you need
• Safe by default: non-string input returns false without throwing
• ReDoS-safe: verified against catastrophic backtracking using recheck
• Zero dependencies

Install

npm install is-valid-css-color
# or
pnpm add is-valid-css-color
# or
yarn add is-valid-css-color
# or
bun add is-valid-css-color

Usage

ESM

import { isValidCssColor } from 'is-valid-css-color';

isValidCssColor('rebeccapurple'); // true
isValidCssColor('#ff0000ff'); // true
isValidCssColor('rgb(255 0 0 / 50%)'); // true
isValidCssColor('not-a-color'); // false

CommonJS

const { isValidCssColor } = require('is-valid-css-color');

isValidCssColor('rebeccapurple'); // true
isValidCssColor('#ff0000ff'); // true
isValidCssColor('rgb(255 0 0 / 50%)'); // true
isValidCssColor('not-a-color'); // false

API

isValidCssColor(color: string): boolean

Returns true if the string is a valid CSS color in any supported format.

Per-format validators

Each format is also exported individually, and works identically under both ESM and CommonJS:

import {
  isValidHex,
  isValidRgb,
  isValidHsl,
  isValidHwb,
  isValidLab,
  isValidLch,
  isValidOklab,
  isValidOklch,
  isValidColorKeyword,
  isValidColorNotation,
} from 'is-valid-css-color';

const {
  isValidHex,
  isValidRgb,
  isValidHsl,
  isValidHwb,
  isValidLab,
  isValidLch,
  isValidOklab,
  isValidOklch,
  isValidColorKeyword,
  isValidColorNotation,
} = require('is-valid-css-color');

All validators accept a string and return a boolean. Non-string input returns false without throwing.

Supported formats

Format	Validator	Example
Color keywords	isValidColorKeyword	red, rebeccapurple, transparent
Hex	isValidHex	#f00, #f00f, #ff0000, #ff0000ff
rgb() / rgba()	isValidRgb	rgb(255, 0, 0), rgb(255 0 0 / 50%)
hsl() / hsla()	isValidHsl	hsl(0, 100%, 50%), hsl(0 100% 50% / 0.5)
hwb()	isValidHwb	hwb(270 0% 0%)
lab()	isValidLab	lab(50 -20 30)
lch()	isValidLch	lch(50 30 270deg)
oklab()	isValidOklab	oklab(0.5 -0.1 0.1)
oklch()	isValidOklch	oklch(0.63 0.26 29)
color()	isValidColorNotation	color(display-p3 1 0 0)

Legacy vs modern syntax

rgb() and hsl() support both syntaxes. All other functions are modern-only.

Legacy (comma-separated): no none, alpha as a bare number or percentage.

isValidCssColor('rgb(255, 0, 0)');
isValidCssColor('rgba(255, 0, 0, 0.5)');
isValidCssColor('hsl(0, 100%, 50%)');
isValidCssColor('hsla(0, 100%, 50%, 0.5)');

Modern (space-separated): none allowed in any channel, alpha after /.

isValidCssColor('rgb(255 0 0)');
isValidCssColor('rgb(255 0 0 / 50%)');
isValidCssColor('hsl(none 100% 50% / 0.5)');

color() color spaces

Supported: srgb, srgb-linear, display-p3, display-p3-linear, a98-rgb, prophoto-rgb, rec2020, xyz, xyz-d50, xyz-d65.

isValidCssColor('color(srgb 1 0 0)');
isValidCssColor('color(prophoto-rgb 0.9 0.1 0.1 / 80%)');

Limitations

This library is designed for high-performance validation of static, literal color strings only. It does not support:

• Dynamic CSS constructs (calc(), var())
• Color manipulation functions (color-mix(), relative color syntax)
• Strings containing inline CSS comments (e.g., rgb(255 /* red */ 0 0))
• Custom color spaces

License

This software is licensed under the MIT License. See the LICENSE for more info.