JS String methods

string.js

String.prototype.sub = function(regex, replacement){  
  var s = this.toString();
  var matches = s.match(regex);
  if ( matches !== null ){
    for(i in matches){
      var item = matches[i];
      if ( !item.escaped() ){
        s = s.replace(item, replacement);
      }
    }
  }
  return s;
}

String.prototype.escaped = function(){
  return ( this.toString().match(/^%{2,}/) !== null );
}

String.prototype.format = function (params){
  var s = this.toString();
  for(var k in params){
    var re = new RegExp("[%]+\\(" + k + "\\)s", 'g');
    s = s.sub(re, params[k]);    
  }
  return s;
}

String.prototype.html_encode = function(){
  return this.toString().replace(/</g, "&lt;").replace(/>/g, "&gt;").replace(/"/g, "&apos;");
}
    
String.prototype.html_decode = function () {
  return $('<div/>').html(this.toString()).text();
}