README.md

contrast

Analyse luminosity contrast ratio

Installation

Run npm install @smockle/contrast to add contrast to your project.

Usage

Shell

# Hexadecimal colors
$ contrast "#000000" "#FFFFFF"

# Shorthand hexadecimal colors
$ contrast "#000" "#FC0"
  # equivalent to `$ contrast "#000000" "#FFCC00"`
$ contrast "#000" "#F8"
  # equivalent to `$ contrast "#000000" "#F8F8F8"`

# Named colors
$ contrast black white

JavaScript & TypeScript

import { Contrast } from "@smockle/contrast";

// Hexadecimal colors
new Contrast("#000000", "#FFFFFF");
  // => {
  //      foreground: {
  //        value: "000000",
  //        R: { value: "00" },
  //        G: { value: "00" },
  //        B: { value: "00" },
  //      },
  //      background: {
  //        value: "FFFFFF",
  //        R: { value: "FF" },
  //        G: { value: "FF" },
  //        B: { value: "FF" },
  //      },
  //      value: 21,
  //    }

// Shorthand hexadecimal colors
new Contrast("#000", "#FC0");
  // equivalent to `new Contrast("#000000", "#FFCC00")`
new Contrast("#000", "#F8");
  // equivalent to `new Contrast("#000000", "#F8F8F8")`

// Named colors
new Contrast("black", "white");

Testing

contrast includes several unit tests. After cloning the contrast repo locally, run npm install in the project folder to install dependencies. Run npm test to execute the tests.

References

• http://juicystudio.com/article/luminositycontrastratioalgorithm.php
• https://www.w3.org/TR/WCAG20/#contrast-ratiodef
• https://www.w3.org/TR/WCAG20/#relativeluminancedef
• https://www.w3.org/Graphics/Color/sRGB.html
• https://stackoverflow.com/a/12894053/1923134