code: function() {
        // inherit instance attributes
        var clonable = this.prototype._instanceAttributes;
        // merge attributes from element
        var a$ = this.attributes;
        for (var i=0, l=a$.length, a; (i<l) && (a=a$[i]); i++) {  
          if (this.isInstanceAttribute(a.name)) {
            clonable[a.name] = a.value;
          }
        }
      }
docs: record clonable attributes from <element>