code: function stripAttrs(tagType, attrs) {
      var ret = extend({}, attrs);
  
      switch (tagType) {
      case 'script':
        // don't care about these properties.
        delete ret.type;
        delete ret.async;
        delete ret.defer;
        break;
      case 'iframe':
        // don't care about these properties.
        delete ret.width;
        delete ret.height;
        delete ret.style;
        delete ret.scrolling;
        delete ret.frameBorder;
        break;
      default:
        // no default case
      }
  
      return ret;
    }
docs: Remove unwanted script/iframe attrs
  
  @param {String} tagType
  @param {Object} attrs
  @return {Object} ret