function Rgb() {
     var red = returnHex(200);
     var green = returnHex(255);
     var blue = returnHex(155);
     var hex = "#" + red + green + blue;
                        
     alert(hex);            
}
  
// Convert to Hex
function returnHex(num) {
     // Hex can store 16 different values in 1 character
     if (num == null) return "00";
     num = num.length < 2 ? "0" + num : num
     return num.toString(16);
}

http://www.devcurry.com/2010/08/convert-rgb-to-hexadecimal-using.html

You have a RGB value and want to convert it into Hexadecimal mode, here’s how to do it using JavaScript.

Convert RGB to Hexadecimal using JavaScript

color

JavaScript