From 755fc8bb1c532eb991459f180eee81367d12016c Mon Sep 17 00:00:00 2001
From: henry <48340699+imwh0im@users.noreply.github.com>
Date: Wed, 7 Jul 2021 11:28:47 +0900
Subject: [PATCH] fix: update plugin advancedFormat `isValid` validation
 (#1566)

---
 src/plugin/advancedFormat/index.js | 5 +++++
 test/plugin/advancedFormat.test.js | 4 ++++
 2 files changed, 9 insertions(+)

diff --git a/src/plugin/advancedFormat/index.js b/src/plugin/advancedFormat/index.js
index 6ebd3f43b..a78296f7a 100644
--- a/src/plugin/advancedFormat/index.js
+++ b/src/plugin/advancedFormat/index.js
@@ -11,6 +11,11 @@ export default (o, c, d) => { // locale needed later
   // extend en locale here
   proto.format = function (formatStr) {
     const locale = this.$locale()
+
+    if (!this.isValid()) {
+      return oldFormat.bind(this)(formatStr)
+    }
+
     const utils = this.$utils()
     const str = formatStr || FORMAT_DEFAULT
     const result = str.replace(/\[([^\]]+)]|Q|wo|ww|w|WW|W|zzz|z|gggg|GGGG|Do|X|x|k{1,2}|S/g, (match) => {
diff --git a/test/plugin/advancedFormat.test.js b/test/plugin/advancedFormat.test.js
index d9512e086..955f94032 100644
--- a/test/plugin/advancedFormat.test.js
+++ b/test/plugin/advancedFormat.test.js
@@ -24,6 +24,10 @@ afterEach(() => {
   MockDate.reset()
 })
 
+it('Format of invalid date', () => {
+  expect(dayjs(null).format('z').toLowerCase()).toEqual(moment(null).format('z').toLowerCase())
+})
+
 it('Format empty string', () => {
   expect(dayjs().format()).toBe(moment().format())
 })