How to calcul two HEX in javascriot code example

Example 1: javascript convert number to hex

yourNumber = parseInt(hexString, 16);

Example 2: to hex javascript

var rgbToHex = function (rgb) { 
  var hex = Number(rgb).toString(16);
  if (hex.length < 2) {
       hex = "0" + hex;
  }
  return hex;
};