Javascript String backup(str)

//Just like you can add methods to your own constructor, you can also add methods and 
//properties to built in classes in JavaScript like Arrays and Objects.

//Add a reverse method to the String 'class' so that every instance of String can call 
//reverse and reverse itself.
  //code here//from www .  j  av a  2 s  .c o m
String.prototype.backup = function(str) {
 var arr = str.split('');
 arr.reverse();
 newStr = arr.join("");
 return newStr;
}