From a92eb6c4dc1437ec920e69484d52984f5921a8ea Mon Sep 17 00:00:00 2001
From: morning <wzl_911@qq.com>
Date: Mon, 23 Nov 2020 17:00:32 +0800
Subject: [PATCH] fix: avoid install installed plugin (#1214)

---
 src/index.js | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/src/index.js b/src/index.js
index 439a392f..6bf5ee65 100644
--- a/src/index.js
+++ b/src/index.js
@@ -387,7 +387,12 @@ dayjs.prototype = proto;
 })
 
 dayjs.extend = (plugin, option) => {
+  if (plugin.installed) {
+    return dayjs
+  }
+
   plugin(option, Dayjs, dayjs)
+  plugin.installed = true
   return dayjs
 }