diff --git a/docs/demo/index.js b/docs/demo/index.js
index 468b170cc..a46312749 100644
--- a/docs/demo/index.js
+++ b/docs/demo/index.js
@@ -17,3 +17,6 @@ dayjs().add(1, 'year').format()
 // subtract
 dayjs().subtract(1, 'year').format()
 
+// diff
+dayjs().diff(dayjs().add(1, 'year'), 'year')
+