jQuery.fn.extend({             autoHeight: function(){                 return this.each(function(){                     var $this = jQuery(this);                     if( !$this.attr('_initAdjustHeight') ){                         $this.attr('_initAdjustHeight', $this.outerHeight());                     }                     _adjustH(this).on('input', function(){                         _adjustH(this);                     });                 });                 /**                  * 重置高度                  * @param {Object} elem                  */                 function _adjustH(elem){                     var $obj = jQuery(elem);                     return $obj.css({height: $obj.attr('_initAdjustHeight'), 'overflow-y': 'hidden'})                             .height( elem.scrollHeight );                 }             }         });         // 使用         $(function(){             $('textarea').autoHeight();         });