A PostCSS plugin for seeing your site as a colorblind person may.
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README.md

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

Examples

All colors, no filter:

All colors

Deuteranopia, no green:

Deuteranopia

Achromatopsia, no color:

Achromatopsia

License

MIT

Author

❤️ Brian Holt, Ben Briggs