Javascript Number isDividable(number)

Number.prototype.isDividable = function (number){
 return this % number == 0;
}

class FizzBuzz{//from   ww  w.  j ava2 s  .  com
 
 constructor(options){
  this._register = options || {
   '3': 'Fizz',
   '5': 'Buzz'
  };
  
  if (!this._register['3']){
   this._register['3'] = 'Fizz';
  }

  if (!this._register['5'])
   this._register['5'] = 'Buzz';
  
 }

 process(number){
  let result = '';
  let register = this._register;

  for (let key in register){
   if (number.isDividable(key))
   result += register[key];
  }

  if (!result)
   return number.toString();
  return result;
 }

 add(options){
  for(let key in options){
   this._register[key] = options[key];
  }
 }
}

module.exports = FizzBuzz;