color.js, my javascript color management library, has reached version 1.0. I'm  surprised about this because I wrote it back in 2008 (hence the incredibly generic name) and have hardly touched it since. The magic of open source I guess. Rather than blathering about the features, heres some snippets:

var Color = net.brehaut.Color; // or 
// var Color = require('./color').Color;

var Green = Color("#00FF00");
var Red = Color({hue: 0, saturation: 1, value: 1});
var Blue = Color("rgba(0,0,255,1)");
var Cyan = Color({hue: 180, saturation: 1, lightness: 0.5});
var Magenta = Color("hsl(300, 100%, 50%)");
var Yellow = Color([255,255,0]);

Red.toCSS() //=> "#FF0000"

Red.shiftHue(45)
   .darkenByRatio(0.5)
   .desaturateByAmount(0.1)
   .toCSS(); //=> "#80630D"

The library supports most CSS string formats, object and array literals, immutable values, three color models (RGB, HSV, and HSL) and has a grab bag of operations on each.

Thanks to Matt Wilson, Tim Baumann, Simon Heimler, Aidan Hobson Sayers, and Michel Vielmetter for their contributions.