rgb2hex

function rgb2hex(sRGB) {
    function getHex(str) {
        let num = Number(str).toString(16);

        return num.length < 2 ? '0' + num : num;
    }
   let result = sRGB.match(/rgb\((\d+),\s*(\d+),\s*(\d+)\s*\)/);
   if(!result) return sRGB;
   return '#'+ getHex(result[1]) + getHex(result[2]) + getHex(result[3]);
}