jquery插件实现多行文本框[textarea]自动高度

jQuery.extend({
    textareaAutosize_dc: function() {
        $("textarea").on("keyup", function(e) {
            var currentEnterCount = $(this).val().split("\n").length;
            var lineHeight = Number($(this).css("line-height").replace("px", ""));
            var enterCount = $(this).attr("enterCount");
            if (currentEnterCount                 //每行减掉固定行高
                $(this).height($(this).height() - lineHeight);
            } else if (currentEnterCount > enterCount) {
                //每行加入固定行高
                $(this).height($(this).height() + lineHeight);
                $(this).attr("enterCount", currentEnterCount);
            }
            //记录当前行高
            $(this).attr("enterCount", currentEnterCount);
        });
    }
});
//调用自动高度
$.textareaAutosize_dc();