The example in this article shows how Javascript can convert color rgb to hexadecimal. Share with you for your reference. The details are as follows:

Usage:

Color(12,34,56);
Color("#fff")
Color("#defdcd")

Implementation code:

// Color conversion
var Color = function() {
  if (!(this instanceof Color)) {
   var color = new Color();
   color._init.apply(color, arguments);
   return color;
  }
  if (arguments.length) {
   this._init.apply(this, arguments);
  }
}
// Set up the get . set methods
var methods = ["red", "green", "blue", "colorValue"];
var defineSetGetMethod = function(fn, methods) {
  var fnPrototype = fn.prototype;
  for (var i = 0; i < methods.length; i++) {
   var methodName = methods[i].charAt(0).toLocaleUpperCase() + methods[i].substring(1);
   fn.prototype['set' + methodName] = new Function("value", "this." + methods[i] + "= value;");
   fn.prototype['get' + methodName] = new Function("return this." + methods[i] + ";");
   fn.prototype['toString'] = new Function('return "rgb("+this.red+","+this.green+","+this.blue+")";');
  }
};
defineSetGetMethod(Color, methods);
// Extends the instance method of the function
var extend = function(fn, option) {
  var fnPrototype = fn.prototype;
  for (var i in option) {
   fnPrototype[i] = option[i];
  }
};
extend(Color, {
  _init : function() {
   if (arguments.length == 3) {
    this.red = arguments[0];
    this.green = arguments[1];
    this.blue = arguments[2];
    this.getColorValue();
   } else {
    var colorValue = arguments[0].replace(/^\#{1}/, "");
    if (colorValue.length == 3) {
     colorValue = colorValue.replace(/(.)/g, '$1$1');
    }
    this.red = parseInt('0x' + colorValue.substring(0, 2), 16);
    this.green = parseInt('0x' + colorValue.substring(2, 4), 16);
    this.blue = parseInt('0x' + colorValue.substring(4), 16);
    this.colorValue = "#" + colorValue;
   }
  },
  getColorValue : function() {
   if (this.colorValue) {
    return this.colorValue;
   }
   var hR = this.red.toString(16);
   var hG = this.green.toString(16);
   var hB = this.blue.toString(16);
   return this.colorValue = "#" + (this.red < 16 ? ("0" + hR) : hR) + (this.green < 16 ? ("0" + hG) : hG) + (this.blue < 16 ? ("0" + hB) : hB);
  }
});

I hope this article is helpful to you in javascript programming.