diff --git a/2019/用node写爬虫.md b/2019/用node写爬虫.md
index de78d29..6cee65e 100644
--- a/2019/用node写爬虫.md
+++ b/2019/用node写爬虫.md
@@ -32,4 +32,4 @@ let $=cheerio.load(res.text)
 
 eg: 获取所有class="button" 的a标签
 
-let btn=$()
\ No newline at end of file
+let btn=$("a.button")
\ No newline at end of file