Calculate if your text is readable on a colored background for colorblind people

colorContrast.js

/**
 * ColorContrast
 * Check if your text is readable on your background for colorblind people
 * 
 * Usage:
 * colorContrast(foregroundColor, backgroundColor)
 * if true, the contrast is sufficient
 */

const hexToRgb = hex => {
	hex = hex.toUpperCase().replace(/^#?([a-f\d])([a-f\d])([a-f\d])$/i, (m, r, g, b) => [r, r, g, g, b, b].join(''));

	const res = hex.match(/^#?([0-9A-F]{2})([0-9A-F]{2})([0-9A-F]{2})$/);

	return res ? {
		r: parseInt(res[1], 16),
		g: parseInt(res[2], 16),
		b: parseInt(res[3], 16)
	} : null;
};

const getsRGB = color => (color / 255) <= 0.03928 ? color / 12.92 : Math.pow((color + 0.055) / 1.055, 2.4);

const getL = color => {
	const {r, g, b} = hexToRgb(color),
		R = getsRGB(r),
		G = getsRGB(g),
		B = getsRGB(b);

	return (0.2126 * R + 0.7152 * G + 0.0722 * B);
};

const colorContrast = (c1, c2) => {
	const L1 = getL(c1),
		L2 = getL(c2),
		ratio = (Math.max(L1, L2) + 0.05) / (Math.min(L1, L2) + 0.05);

	return ratio >= 3;
};