code: function() {
          var me = this,
              isValid = me.isValid();
          if (isValid !== me.wasValid) {
              me.wasValid = isValid;
              me.fireEvent('validitychange', me, isValid);
          }
          return isValid;
      }
docs: Returns whether or not the field value is currently valid by {@link #getErrors validating} the field's current
  value, and fires the {@link #validitychange} event if the field's validity has changed since the last validation.
  **Note**: {@link #disabled} fields are always treated as valid.
  
  Custom implementations of this method are allowed to have side-effects such as triggering error message display.
  To validate without side-effects, use {@link #isValid}.
  
  @return {Boolean} True if the value is valid, else false