Here are 9 useful Javascript libraries which allow you to perform many different manipulations on colors.

Colorify

Colorify is a script written in Javascript, that allows you to extract colors from images, and manipulates them. From a simple plain color, based on the dominant color, to a beautiful gradient based on the image edges colors, colorify.js will spice up your designs!

Random Color

A tiny script for generating attractive colors.

Please.js

Please.js is a polite companion that wants to help you make your projects beautiful. It uses HSV color space to create random pleasing colors as well as color schemes based on a given color. It has two core functions and a bunch of little helpers for you to use.

sweep.js

sweep.js is a small JavaScript library (5kb zipped) that enables proper color transitions through the HSL and HUSL spaces. Ordinary CSS transitions and existing frameworks convert HSL colors to RGB before transitioning. sweep.js addresses this by letting you transition through the color spectrum.

Kolorwheel

This small javascript library is designed for developers, who have no talent and time to create professional color palettes. Pick a base color, build a transformation chain, and if you haven’t choosen too weird parameters, the result will be satisfactory.

gradStop.js

JavaScript micro library to generate monotone color schemes and equidistant gradient stops

Chance.js

Chance is a minimalist generator of random strings, numbers, etc. to help reduce some monotony particularly while writing automated tests or anywhere else you need anything random.

chroma.js

Tiny JavaScript library for dealing with colors! Here are a couple of things chroma.js can do for you – read colors from a wide range of formats, analyze and manipulate colors, convert colors into wide range of formats, linear and bezier interpolation in different color spaces. Aside from that, chroma.js can also help you generate nice colors using various methods, for instance to be used in color palette for maps or data visualizations.

Vibrant.js

Extract prominent colors from an image. Vibrant.js is a javascript port of the awesome Palette class in the Android support library.