var colorcode ="rgba(0, 0, 0, 0.74)";

var finalCode = rgba2hex(colorcode)

function rgba2hex(orig) {
      var a, isPercent,
        rgb = orig.replace(/s/g, '').match(/^rgba?((d+),(d+),(d+),?([^,s)]+)?/i),
        alpha = (rgb && rgb[4] || "").trim(),
        hex = rgb ?
        (rgb[1] | 1 << 8).toString(16).slice(1) +
        (rgb[2] | 1 << 8).toString(16).slice(1) +
        (rgb[3] | 1 << 8).toString(16).slice(1) : orig;
          if (alpha !== "") {
            a= alpha;
          }else{
             a = 01;
          }
      hex = hex+a;
      return hex;
}