PostCSS Colorblind Plugin

Why?

The biggest reason is that as many developers don't have problems seeing color, they never stop to consider that their (or their colleagues') choices of colors make their website unusable and frustrating to those who can't see some shades of color. It's not even a small problem either; lots of people struggle with red and green.

However, there are JavaScript bookmarklets that let you do this on the fly without having to run a build step. I built this with the thought in mind you could create an automated step to create a report of how you're doing with color.

And lastly, building plugins for PostCSS is so damn easy and fun.

This plugin currently works for any place a CSS color is declared, whether it's a named color (like red or papayawhip), hex, rgb, rgba, hsl or hsla. It supports gradients and will also convert any linked images into color adjusted embedded data.

Install

npm install postcss-colorblind

Setup

To make this module as effective as possible, make this the last module that modifies your CSS.

var fs = require("fs")
var postcss = require("postcss")
var colorblindPlugin = require("postcss-colorblind");

var css = fs.readFileSync("input.css", "utf8");

postcss()
  .use(colorblindPlugin({method:'achromatopsia'}))
  .process(css)
  .then(function(result) {
    fs.writeFileSync('output.css', result.css);
  });

Parameters

method (default: deuteranopia)

The module expects an object with a method name that it can give to the color-blind module. Thus, as of writing, any of the following will work:

protanomaly
protanopia
deuteranomaly
deuteranopia
tritanomaly
tritanopia
achromatomaly
achromatopsia

Color Blindness Table

Borrowed from @skratchdot's color-blind, the dependency of this module.

Group
Trichromat 3 good cones	Normal
Anomalous Trichromat 2 good cones, 1 bad	Protanomaly low red	Deuteranomaly low green	Tritanomaly low blue
Dichromat 2 good cones, 1 blind	Protanopia no red	Deuteranopia no green	Tritanopia no blue
Monochromat 1 good cone, 2 blind/bad	Achromatomaly almost no color	Achromatopsia no color