@adeira/css-colors

Utility functions for working with CSS/HTML colors.

Installation

yarn add @adeira/css-colors

Usage

Get color keywords

import { cssColorNames } from '@adeira/css-colors';

cssColorNames.get('rebeccapurple'); // => #663399

The imported cssColorNames is a Map of all CSS keywords, so you can use any available Map methods.

Is it a color?

import { isColor } from '@adeira/css-colors';

isColor('#663399'); // true
isColor('rebeccapurple'); // true
isColor('rgb(255, 255, 128)'); // true
isColor('transparent'); // true
isColor('currentcolor'); // true
isColor('hsl(50, 33%, 25)'); // false (last number should be 25%)

What is the color contrast ratio?

This function takes triplet of colors for foreground and background colors and calculates their contrast ratio (from 1:1 for no contrast up to 25:1 for excellent contrast):

import { calculateContrastRatio } from '@adeira/css-colors';

calculateContrastRatio([130, 242, 75], [119, 46, 242]); // 4.27 (4.27:1)

See: https://developer.mozilla.org/en-US/docs/Web/Accessibility/Understanding_WCAG/Perceivable/Color_contrast

Is the pair of colors accessible?

Allows you to decide whether a pair of two colors (typically foreground and background) is accessible:

import { isAccessible } from '@adeira/css-colors';

isAccessible([0, 0, 0], [255, 255, 255]); // true (black and white combo)

// optionally, you can specify context of these colors and success criteria for accessibility:
isAccessible([64, 32, 17], [201, 120, 136], 'NORMAL_TEXT', 'AAA'); // false
isAccessible([64, 32, 17], [201, 120, 136], 'NORMAL_TEXT', 'AA'); // true
isAccessible([64, 32, 17], [201, 120, 136], 'LARGE_TEXT', 'AAA'); // true
isAccessible([64, 32, 17], [201, 120, 136], 'GRAPHICAL_OBJECTS'); // true

Note on colors accessibility: it can happen that some backgrounds are never accessible under AAA criteria. For example #FF1A1A always fails "normal text" test for AAA criteria (no matter whether you choose completely white or completely black font).

Normalize colors

import { normalizeColor } from '@adeira/css-colors';

normalizeColor('#639'); // #639
normalizeColor('#663399'); // #639
normalizeColor('rebeccapurple'); // #639

HEX to HEX

import { hex3ToHex6, hex6ToHex3 } from '@adeira/css-colors';

hex3ToHex6('#639'); // #663399
hex6ToHex3('#663399'); // #639

Is the color bright or dark? (DEPRECATED)

This function can be used to detect whether the color is bright or dark, so you can decide whether you should use white or black text for the color background (or vice versa):

import { isDark, isBright } from '@adeira/css-colors';

isDark([0, 0, 0]); // true (it's black)
isBright([0, 0, 0]); // false

isDark([144, 238, 144]); // false (lightgreen)
isBright([144, 238, 144]); // true

isDark([255, 255, 255]); // false (it's white)
isBright([255, 255, 255]); // true

Please note that while this function is simple, it takes into account only one color. Consider using calculateContrastRatio and/or isAccessible described above where you can specify 2 colors (for example, text and its background).