Javascript String replaceAll(org, dest)

String.prototype.replaceAll = function(org, dest) {
    return this.split(org).join(dest);
}

String.prototype.replaceAll = function(org, dest) {
 var data = this;
 if (org instanceof Array) {
  org.forEach(function(elm) {
   data = data.split(elm).join(dest);/*from   w  ww. ja v  a 2s .  com*/
  });
  return data;
 } else {
  return data.split(org).join(dest);
 }
};

var common = {};

common.randomAlphaNumeric = function(digit) {
 var text = '';
 var possible = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789';
 for (var i = 0; i < digit; i++) {
  text += possible.charAt(Math.floor(Math.random() * possible.length));
 }
 return text;
};