getBrightness color function

getBrightness()

var getBrightness = function(hex) {

    var rgb = 'rgb(' + (hex = hex.replace('#', '')).match(new RegExp('(.{' + hex.length/3 + '})', 'g')).map(function(l) { return parseInt(hex.length%2 ? l+l : l, 16); }).join(',') + ')';

    // Get array of RGB values
    rgb = rgb.replace(/[^\d,]/g, '').split(',');

    var r = rgb[0], g = rgb[1], b = rgb[2];

    var brightness = Math.floor((r * 299 + g * 587 + b * 114) / 1000);
    
    return brightness;
}