javascript-module-pattern.js

// From JavaScript The Good Parts

String.prototype.deentityify = (function () {
  var entity = {
    quot: '"',
    lt:   '<',
    gt: '>'
  };
  return function ( ) {
    return this.replace(/&([^&;]+);/g, function (a, b) {
      var r = entity[b];
      return typeof r === 'string' ? r : a;
    });
  };
}());

document.writeln('&lt;&quot;&gt;'.deentityify());  // <">