I have function for auto resize textarea height, it works on init and keyup:

autoHeight: function () {
        function autoHeight_(element) {
          //  $(element).parents('.rowb').height(element.scrollHeight);
            return jQuery(element)
                .css({ "height": "auto", "overflow-y": "hidden" })
                .height(element.scrollHeight);
        }
        return this.each(function() {
            autoHeight_(this).on("input", function() {
                autoHeight_(this);
            });
        });
    }

It works, but problem is if I increase textarea height by mouse and then typo something it does't save prev height. How can i use autoheight only if content is bigger then textarea height?