textarea自适应高度

(function ($) {
    $.fn.autoTextarea = function (options) {
        var defaults = {
            maxHeight: null,
            minHeight: $(this).height()
        };
        var opts = $.extend({}, defaults, options);
        return $(this).each(function () {
            $(this).bind("paste cut keydown keyup focus blur", function () {
                var height, style = this.style;
                this.style.height = opts.minHeight + 'px';
                if (this.scrollHeight > opts.minHeight) {
                    if (opts.maxHeight && this.scrollHeight > opts.maxHeight) {
                        height = opts.maxHeight;
                        style.overflowY = 'scroll';
                    } else {
                        height = this.scrollHeight;
                        style.overflowY = 'hidden';
                    }
                    style.height = height + 'px';
                }
            });
        });
    };
})(jQuery);
$("textarea#txt_show").autoTextarea({
    maxHeight: 2000,
    minHeight: 80
});