Khrôma

A collection of functions for manipulating CSS colors, inspired by SASS.

Features

• Small: the entire library weighs ~5kb (min + gzip) and has no dependencies.
• Fast: in our benchmark suite functions are executed at ~0.0025ms per call on a mid-2014 MBP.
• Flexible: All valid CSS colors are supported.
• SASS-like: if you're familiar with SASS you should feel right at home.

Install

npm install --save khroma

Usage

import {red, isDark, darken, change} from 'khroma';

red ( '#ffffff' ); // => 255
isDark ( 'white' ); // => false
darken ( 'hsl(0, 5%, 100%)', 50 ); // => 'hsl(0, 5%, 50%)'
change ( 'rgb(255, 255, 255)', { a: 0.5 } ); // => 'rgba(255, 255, 255, 0.5)'

Functions

These are all the provided functions, for each of them below you can find a short description, its interface and examples.

Create

These functions create a new color given the provided channels.

hex

Alias for rgba.

rgb

Alias for rgba.

rgba

Creates a new color given its rgba channels, the alpha channel is optional.

function rgba ( r: string, g: number, b: number, a: number = 1 ): string;

rgba ( 255, 204, 0 ); // => '#ffcc00'
rgba ( 255, 204, 0, 0.5 ); // => 'rgba(255, 204, 0, 0.5)'

hsl

Alias for hsla.

hsla

Creates a new color given its hsla channels, the alpha channel is optional.

function hsla ( h: number, s: number, l: number, a: number = 1 ): string;

hsla ( 0, 50, 100 ); // => 'hsl(0, 50%, 100%)'
hsla ( 10, 50, 100, 0.5 ); // => 'hsla(10, 50%, 100%, 0.5)'

Convert

These functions convert supported colors to a specific format.

toKeyword

Convert a color to the keyword format, when possible.

function toKeyword ( color: string ): string | undefined;

toKeyword ( '#ff0000' ); // => 'red'
toKeyword ( '#ffcc00' ); // => undefined

toHex

Convert a color to the HEX format.

function toHex ( color: string ): string;

toHex ( 'red' ); // => '#ff0000'
toHex ( '#ff0000' ); // => '#ff0000'

toRgba

Convert a color to the RGBA format.

function toRgba ( color: string ): string;

toRgba ( 'red' ); // => 'rgb(255, 0, 0)'
toRgba ( '#ff0000' ); // => 'rgb(255, 0, 0)'
toRgba ( '#00000088' ); // => 'rgba(0, 0, 0, 0.5333333333)'

toHsla

Convert a color to the HSLA format.

function toHsla ( color: string ): string;

toHsla ( 'red' ); // => 'hsl(0, 100%, 50%)'
toHsla ( '#ff0000' ); // => 'hsl(0, 100%, 50%)'
toHsla ( 'rgb(255, 0, 0)' ); // => 'hsl(0, 100%, 50%)'

Get _channel

These functions get a single channel from the provided color.

channel

Gets any single channel of the color.

function channel ( color: string, channel: 'r' | 'g' | 'b' | 'h' | 's' | 'l' | 'a' ): number;

channel ( '#ffcc00', 'r' ); // => 255
channel ( '#ffcc00', 'h' ); // => 48
channel ( '#ffcc00', 'a' ); // => 1

red

Gets the red channel of the color.

function red ( color: string ): number;

red ( '#ffcc00' ); // => 255

green

Gets the green channel of the color.

function green ( color: string ): number;

green ( '#ffcc00' ); // => 204

blue

Gets the blue channel of the color.

function blue ( color: string ): number;

blue ( '#ffcc00' ); // => 0

hue

Gets the hue channel of the color.

function hue ( color: string ): number;

hue ( 'hsl(0, 50%, 100%)' ); // => 0

saturation

Gets the saturation channel of the color.

function saturation ( color: string ): number;

saturation ( 'hsl(0, 50%, 100%)' ); // => 50

lightness

Gets the lightness channel of the color.

function lightness ( color: string ): number;

lightness ( 'hsl(0, 50%, 100%)' ); // => 100

alpha

Gets the alpha channel of the color.

function alpha ( color: string ): number;

alpha ( '#ffcc00' ); // => 1
alpha ( 'rgba(255, 205, 0, 0.5)' ); // => 0.5

opacity

Alias for alpha.

Get _more

These functions get some other information from the provided color.

contrast

Gets the contrast in luminance between two colors.

Contrast values go between 1 and 10. 1 means same color, >= 4 means decent contrast, >= 7 means great contrast, 10 means great contrast.

function contrast ( color1: string, color2: string ): number;

contrast ( '#000000', '#000000' ); // => 1
contrast ( '#000000', '#ffffff' ); // => 10
contrast ( '#888888', '#ffffff' ); // => 4.0617165366

luminance

Gets the relative luminance of the color.

function luminance ( color: string ): number;

luminance ( 'black' ); // => 0
luminance ( 'white' ); // => 1
luminance ( '#ffcc00' ); // => 0.6444573127

isDark

Checks if the provided color is a dark color.

function isDark ( color: string ): number;

isDark ( 'black' ); // => true
isDark ( 'white' ); // => false
isDark ( '#ffcc00' ); // => false

isLight

Checks if the provided color is a light color.

function isLight ( color: string ): number;

isLight ( 'black' ); // => false
isLight ( 'white' ); // => true
isLight ( '#ffcc00' ); // => true

isTransparent

Checks if the provided color is a transparent color.

function isTransparent ( color: string ): boolean;

isTransparent ( 'transparent' ); // => true
isTransparent ( '#ffcc0000' ); // => true
isTransparent ( '#ffcc00' ); // => false

isValid

Checks if the provided color is a valid color.

function isLight ( color: string ): boolean;

isValid ( 'black' ); // => true
isValid ( '#ffcc00' ); // => true
isValid ( '#wtf' ); // => false

Edit _channel

These functions change a single channel of the provided color.

saturate

Increases the saturation channel of the color.

function saturate ( color: string, amount: number ): string;

saturate ( 'hsl(0, 50%, 50%)', 25 ); // => 'hsl(0, 75%, 50%)'

desaturate

Decreases the saturation channel of the color.

function desaturate ( color: string, amount: number ): string;

desaturate ( 'hsl(0, 50%, 50%)', 25 ); // => 'hsl(0, 25%, 50%)'

lighten

Increases the lightness channel of the color.

function lighten ( color: string, amount: number ): string;

lighten ( 'hsl(0, 50%, 50%)', 25 ); // => 'hsl(0, 50%, 75%)'

darken

Decreases the lightness channel of the color.

function darken ( color: string, amount: number ): string;

darken ( 'hsl(0, 50%, 50%)', 25 ); // => 'hsl(0, 50%, 25%)'

opacify

Increases the opacity channel of the color.

function opacify ( color: string, amount: number ): string;

opacify ( 'rgba(255, 204, 0, 0.5)', 0.25 ); // => 'rgba(255, 204, 0, 0.75)'

fadeIn

Alias for opacify.

transparentize

Decreases the opacity channel of the color.

function transparentize ( color: string, amount: number ): string;

transparentize ( 'rgba(255, 204, 0, 0.5)', 0.25 ); // => 'rgba(255, 204, 0, 0.25)'

fadeOut

Alias for transparentize.

rgba (alt)

Sets a new value for the opacity channel.

function rgba ( color: string, amount: number ): string;

rgba ( 'rgba(255, 204, 0, 0.5)', 0.1 ); // => 'rgba(255, 204, 0, 0.1)'

complement

Gets the complement of the color, rotating its hue channel by 180 degrees.

function complement ( color: string ): string;

complement ( '#ffcc00' ); // => 'hsl(228, 100%, 50%)'

grayscale

Gets the grayscale version of the color, setting its saturation to 0.

function grayscale ( color: string ): string;

grayscale ( '#ffcc00' ); // => 'hsl(48, 0%, 50%)'

Edit _more

These functions can/will change more than a single channel at once of the provided color.

adjust

Increases or decreases the value of any channel of the color.

function adjust ( color: string, channels: Record<'r' | 'g' | 'b' | 'h' | 's' | 'l' | 'a', number> ): string;

adjust ( '#ffcc00', { r: -10, g: 200 } ); // => '#f5ff00'
adjust ( '#ffcc00', { a: -0.5 } ); // => 'rgba(255, 204, 0, 0.5)'
adjust ( '#ffcc00', { h: 50, l: -30 } ); // => 'hsl(98, 100%, 20%)'

change

Sets a new value for any channel of the color.

function change ( color: string, channels: Record<'r' | 'g' | 'b' | 'h' | 's' | 'l' | 'a', number> ): string;

change ( '#ffcc00', { r: 10, g: 200 } ); // => '#0ac800'
change ( '#ffcc00', { a: 0.5 } ); // => 'rgba(255, 204, 0, 0.5)'
change ( '#ffcc00', { h: 50, l: 30 } ); // => 'hsl(50, 100%, 30%)'

invert

Gets the inverse of the color.

function invert ( color: string, weight: number = 100 ): string;

invert ( '#ffcc00' ); // => '#0033ff'
invert ( '#ffcc00', 50 ); // => '#808080'

mix

Mixes two colors together.

function mix ( color1: string, color2: string, weight: number = 50 ): string;

mix ( 'red', 'blue' ); // => '#800080'
mix ( 'red', 'blue', 15 ); // => '#2600d9'

scale

Scales any channel of the color.

function scale ( color: string, channels: Record<'r' | 'g' | 'b' | 'h' | 's' | 'l' | 'a', number> ): string;

scale ( '#ffcc00', { r: -50, b: 10 } ); // => '#80cc1a'

License

MIT © Fabio Spampinato, Andrew Maney

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