String.prototype.extend({
  stripTags: function() {
    return this.replace(/<\/?[^>]+>/gi, '');
  },

  escapeHTML: function() {
    var div = document.createElement('div');
    var text = document.createTextNode(this);
    div.appendChild(text);
    return div.innerHTML;
  },

  unescapeHTML: function() {
    var div = document.createElement('div');
    div.innerHTML = this.stripTags();
    return div.childNodes[0].nodeValue;
  }
});