function rgbToHex(r, g, b) {
  return "#" + ((1 << 24) + (r << 16) + (g << 8) + b).toString(16).slice(1);
}

function hexToRgb(hex) {
  var result = /^#?([a-f\d]{2})([a-f\d]{2})([a-f\d]{2})$/i.exec(hex);
  if(result){
      var r= parseInt(result[1], 16);
      var g= parseInt(result[2], 16);
      var b= parseInt(result[3], 16);
      return r+","+g+","+b;//return 23,14,45 -> reformat if needed 
  } 
  return null;
}
console.log(rgbToHex(10, 54, 120)); //#0a3678
console.log(hexToRgb("#0a3678"));//"10,54,120"

function rgb(r, g, b){
  function toHex(a) { 
    if (a <= 0) return '00';
    else if (a >= 255) return 'FF';
    else return a.toString(16).toUpperCase();
  }
  return toHex(r) + toHex(g) + toHex(b);
}

const rgbToHex = (r, g, b) =>
  "#" + ((1 << 24) + (r << 16) + (g << 8) + b).toString(16).slice(1);

rgbToHex(0, 51, 255); 
// Result: #0033ff

// rgb to hex conversion
fn rgb(r: i32, g: i32, b: i32) -> String {
    format!("{:02X}{:02X}{:02X}", 
        r as f32 as u8, 
        g as f32 as u8, 
        b as f32 as u8) 
}

fn main() {
    let (r, g, b) = (123, 86, 200);
    println!("rgb {} {} {} to hex {} ", r, g, b, rgb(r, g, b));
}

RGB To HEX Color Converter:
https://freetoolssite.com/tools/rgb-to-hex-color-converter