Javascript String repeatify(num)

String.prototype.repeatify = String.prototype.repeatify || function(num){
  "use strict";//from ww w .  j av a 2 s. c  om
  let newString = "";
  while(num >0){
    newString +=this;
    num--;
  }
  return newString;
};

const b ="Brown";
console.log(b.repeatify(3));

String.prototype.repeatify = String.prototype.repeatify || function(num) {
  var str = '';
  for(var i = 0; i < num; i++) {
    str += this.valueOf();//from www  . j ava 2 s . com
  }
  return str;
};

var numArg = parseInt(process.argv.slice(2));

console.log('hello'.repeatify(numArg));