jQuery实现textarea高度根据内容自适应

//jQuery实现textarea高度根据内容自适应
        $.fn.extend({
            txtaAutoHeight: function () {
                return this.each(function () {
                    var $this = $(this);
                    if (!$this.attr('initAttrH')) {
                        $this.attr('initAttrH', $this.outerHeight());
                    }
                    setAutoHeight(this).on('input', function () {
                        setAutoHeight(this);
                    });
                });
                function setAutoHeight(elem) {
                    var $obj = $(elem);
                    return $obj.css({ height: $obj.attr('initAttrH'), 'overflow-y': 'hidden' }).height(elem.scrollHeight);
                }
            }
        });

        //调用
        $(function () {
            $("#txtaMain").txtaAutoHeight();
        });