Browser/node color library. Implicit color space conversions, chainable channel methods and CSS convenience methods. RGB, HSV, HSL, CMYK with alpha channel



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JavaScript color calculation toolkit for node.js and the browser.


  • RGB, HSV, HSL, and CMYK colorspace support (experimental implementations of LAB and XYZ)
  • Legal values for all channels are 0..1
  • Instances are immutable -- a new object is created for each manipulation
  • All internal calculations are done using floating point, so very little precision is lost due to rounding errors when converting between colorspaces
  • Alpha channel support
  • Extensible architecture -- implement your own colorspaces easily
  • Chainable color manipulation
  • Seamless conversion between colorspaces
  • Outputs as hex, rgb(...), or rgba(...).

Module support:

  • CommonJS / Node
  • AMD / RequireJS
  • Vanilla JS (installs itself on one.color)

Package managers:

  • npm: npm install onecolor
  • bower: bower install color

Small sizes:

  • one-color.js (Basic RGB, HSV, HSL)
  • one-color-all.js (Full RGB, HSV, HSL, CMYK, XYZ, LAB, named colors, helper functions)


In the browser (change one-color.js to one-color-all.js to gain named color support):

<script src='one-color.js'></script>
    alert('Hello, ' + one.color('#650042').lightness(.3).green(.4).hex() + ' world!');

In node.js (after npm install onecolor):

var color = require('onecolor');
console.warn(color('rgba(100%, 0%, 0%, .5)').alpha(.4).cssa()); // 'rgba(255,0,0,0.4)'

one.color is the parser. All of the above return color instances in the relevant color space with the channel values (0..1) as instance variables:

var myColor = one.color('#a9d91d');
myColor instanceof one.color.RGB; // true // 0.6627450980392157

You can also parse named CSS colors (works out of the box in node.js, but the requires the slightly bigger one-color-all.js build in the browser):

one.color('maroon').lightness(.3).hex() // '#990000'

To turn a color instance back into a string, use the hex(), css(), and cssa() methods:

one.color('rgb(124, 96, 200)').hex() // '#7c60c8'
one.color('#bb7b81').cssa() // 'rgba(187,123,129,1)'

Color instances have getters/setters for all channels in all supported colorspaces (red(), green(), blue(), hue(), saturation(), lightness(), value(), alpha(), etc.). Thus you don't need to think about which colorspace you're in. All the necessary conversions happen automatically:

one.color('#ff0000') // Red in RGB
    .green(1) // Set green to the max value, producing yellow (still RGB)
    .hue(.5, true) // Add 180 degrees to the hue, implicitly converting to HSV
    .hex() // Dump as RGB hex syntax: '#2222ff'

When called without any arguments, they return the current value of the channel (0..1):

one.color('#09ffdd').green() // 1
one.color('#09ffdd').saturation() // 0.9647058823529412

When called with a single numerical argument (0..1), a new color object is returned with that channel replaced:

var myColor = one.color('#00ddff'); // .5

// ... but as the objects are immutable, the original object retains its value: // 0

When called with a single numerical argument (0..1) and true as the second argument, a new value is returned with that channel adjusted:

one.color('#ff0000') // Red
    .red(-.1, true) // Adjust red channel by -0.1
    .hex() // '#e60000'

Alpha channel

All color instances have an alpha channel (0..1), defaulting to 1 (opaque). You can simply ignore it if you don't need it.

It's preserved when converting between colorspaces:

one.color('rgba(10, 20, 30, .8)')
    .alpha() // 0.8

Comparing color objects

If you need to know whether two colors represent the same 8 bit color, regardless of colorspace, compare their hex() values:

one.color('#f00').hex() === one.color('#e00').red(1).hex() // true

Use the equals method to compare two color instances within a certain epsilon (defaults to 1e-9).

one.color('#e00').lightness(.00001, true).equals(one.color('#e00'), 1e-5) // false
one.color('#e00').lightness(.000001, true).equals(one.color('#e00'), 1e-5) // true

Before comparing the equals method converts the other color to the right colorspace, so you don't need to convert explicitly in this case either:

one.color('#e00').hsv().equals(one.color('#e00')) // true

API overview

Color parser function, the recommended way to create a color instance:

one.color('#a9d91d') // Regular hex syntax
one.color('a9d91d') // hex syntax, # is optional
one.color('#eee') // Short hex syntax
one.color('rgb(124, 96, 200)') // CSS rgb syntax
one.color('rgb(99%, 40%, 0%)') // CSS rgb syntax with percentages
one.color('rgba(124, 96, 200, .4)') // CSS rgba syntax
one.color('hsl(120, 75%, 75%)') // CSS hsl syntax
one.color('hsla(120, 75%, 75%, .1)') // CSS hsla syntax
one.color('hsv(220, 47%, 12%)') // CSS hsv syntax (non-standard)
one.color('hsva(120, 75%, 75%, 0)') // CSS hsva syntax (non-standard)
one.color([0, 4, 255, 120]) // CanvasPixelArray entry, RGBA
one.color(["RGB", .5, .1, .6, .9]) // The output format of color.toJSON()

The slightly bigger one-color-all.js build adds support for the standard suite of named CSS colors:


Existing one.color instances pass through unchanged, which is useful in APIs where you want to accept either a string or a color instance:

one.color(one.color('#fff')) // Same as one.color('#fff')

Serialization methods:

color.hex() // 6-digit hex string: '#bda65b'
color.css() // CSS rgb syntax: 'rgb(10,128,220)'
color.cssa() // CSS rgba syntax: 'rgba(10,128,220,0.8)'
color.toString() // For debugging: '[one.color.RGB: Red=0.3 Green=0.8 Blue=0 Alpha=1]'
color.toJSON() // ["RGB"|"HSV"|"HSL", <number>, <number>, <number>, <number>]

Getters -- return the value of the channel (converts to other colorspaces as needed):
color.cyan()    // one-color-all.js and node.js only
color.magenta() // one-color-all.js and node.js only
color.yellow()  // one-color-all.js and node.js only   // one-color-all.js and node.js only

Setters -- return new color instances with one channel changed:<number>)<number>)<number>)
color.cyan(<number>)    // one-color-all.js and node.js only
color.magenta(<number>) // one-color-all.js and node.js only
color.yellow(<number>)  // one-color-all.js and node.js only<number>)   // one-color-all.js and node.js only

Adjusters -- return new color instances with the channel adjusted by the specified delta (0..1):<number>, true)<number>, true)<number>, true)
color.hue(<number>, true)
color.saturation(<number>, true)
color.value(<number>, true)
color.lightness(<number>, true)
color.alpha(<number>, true)
color.cyan(<number>, true)    // one-color-all.js and node.js only
color.magenta(<number>, true) // one-color-all.js and node.js only
color.yellow(<number>, true)  // one-color-all.js and node.js only<number>, true)   // one-color-all.js and node.js only

Comparison with other color objects, returns true or false (epsilon defaults to 1e-9):

color.equals(otherColor[, <epsilon>])

Mostly for internal (and plugin) use:

"Low level" constructors, accept 3 or 4 numerical arguments (0..1):

new one.color.RGB(<red>, <green>, <blue>[, <alpha>])
new one.color.HSL(<hue>, <saturation>, <lightness>[, <alpha>])
new one.color.HSV(<hue>, <saturation>, <value>[, <alpha>])

The one-color-all.js build includes CMYK support:

new one.color.CMYK(<cyan>, <magenta>, <yellow>, <black>[, <alpha>])

All color instances have rgb(), hsv(), and hsl() methods for explicitly converting to another color space. Like the setter and adjuster methods they return a new color object representing the same color in another color space.

If for some reason you need to get all the channel values in a specific colorspace, do an explicit conversion first to cut down on the number of implicit conversions:

var myColor = one.color('#0620ff').lightness(+.3).rgb();
// Alerts '0 0.06265060240963878 0.5999999999999999':
alert( + ' ' + + ' ' +;


git clone
cd one-color
npm install
npm run build

If you aren't up for a complete installation, there are pre-built packages in the repository as well as the npm package:


one.color is licensed under a standard 2-clause BSD license -- see the LICENSE file for details.