//最小高度和最大高度默认    $("#textarea1").textareaAutoHeight();    //最大高度为100px    $("#textarea2").textareaAutoHeight({ maxHeight:100 });    //最小高度为50px，最大高度为200px    $("#textarea3").textareaAutoHeight({ minHeight:50, maxHeight:200 });     $.fn.extend({      textareaAutoHeight: function (options) {          this._options = {              minHeight: 0,              maxHeight: 1000          }             this.init = function () {              for (var p in options) {                  this._options[p] = options[p];              }              if (this._options.minHeight == 0) {                  this._options.minHeight=parseFloat($(this).height());              }              for (var p in this._options) {                  if ($(this).attr(p) == null) {                      $(this).attr(p, this._options[p]);                  }              }              $(this).keyup(this.resetHeight).change(this.resetHeight)              .focus(this.resetHeight);          }          this.resetHeight = function () {              var _minHeight = parseFloat($(this).attr("minHeight"));              var _maxHeight = parseFloat($(this).attr("maxHeight"));                 if (!$.browser.msie) {                  $(this).height(0);              }              var h = parseFloat(this.scrollHeight);              h = h < _minHeight ? _minHeight :                          h > _maxHeight ? _maxHeight : h;              $(this).height(h).scrollTop(h);              if (h >= _maxHeight) {                  $(this).css("overflow-y", "scroll");              }              else {                  $(this).css("overflow-y", "hidden");              }          }          this.init();      }  });