Generate colors with JavaScript

I want to add functionality to my application that randomly generates a color scheme based on some color, for example #0080C8. So, when I click a button, it takes the base color and generates a list of colors, each generated with its own parameter, for example, lighten by 20% for one, and darken by 10% for another one. So, what I wonder about, is there a ready-to-use JS library that has such methods like darken, lighten,开发者_StackOverflow中文版 and so on?

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See this JQuery plugin:

http://www.xarg.org/project/jquery-color-plugin-xcolor/

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color blender is an oldie but a goodie. i love it. http://meyerweb.com/eric/tools/color-blend/