core.js

function matchRule(str, rule) {
	return new RegExp(rule.split("*").join(".*")).test(str);
}

// env [{match: '*.allizom.org', color: '#f00'}]
function getColorFromUrl(env, url) {
	var color = null

	env.forEach(function(env) {
		if (matchRule(url, env.match)) {
			color = env.color
		}
	})

	return color
}

function invertColor(hex, bw) {
	if (hex.indexOf('#') === 0) {
		hex = hex.slice(1);
	}
 
  // convert 3-digit hex to 6-digits.
  if (hex.length === 3) {
    hex = hex[0] + hex[0] + hex[1] + hex[1] + hex[2] + hex[2];
  }
  if (hex.length !== 6) {
    throw new Error('Invalid HEX color.');
  }
  var r = parseInt(hex.slice(0, 2), 16),
    g = parseInt(hex.slice(2, 4), 16),
    b = parseInt(hex.slice(4, 6), 16);
  if (bw) {
    // http://stackoverflow.com/a/3943023/112731
    return (r * 0.299 + g * 0.587 + b * 0.114) > 186
      ? '#000000'
      : '#FFFFFF';
  }
  // invert color components
  r = (255 - r).toString(16);
  g = (255 - g).toString(16);
  b = (255 - b).toString(16);
  // pad each with zeros and return
  return "#" + padZero(r) + padZero(g) + padZero(b);
}

function colorLuminance(hex, lum) {

	// validate hex string
	hex = String(hex).replace(/[^0-9a-f]/gi, '');
	if (hex.length < 6) {
		hex = hex[0]+hex[0]+hex[1]+hex[1]+hex[2]+hex[2];
	}
	lum = lum || 0;

	// convert to decimal and change luminosity
	var rgb = "#", c, i;
	for (i = 0; i < 3; i++) {
		c = parseInt(hex.substr(i*2,2), 16);
		c = Math.round(Math.min(Math.max(0, c + (c * lum)), 255)).toString(16);
		rgb += ("00"+c).substr(c.length);
	}

	return rgb;
}