From 11631b733bae884a0205bca91ef5cc9f9bca0def Mon Sep 17 00:00:00 2001
From: waruneeauy <warunee.auy@gmail.com>
Date: Wed, 16 Jul 2025 15:09:14 +0700
Subject: [PATCH] =?UTF-8?q?=E0=B9=81=E0=B8=81=E0=B9=89=20error=20Undefined?=
 =?UTF-8?q?=20NaN=20=E0=B8=82=E0=B8=AD=E0=B8=87=20month-picker?=
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---
 src/stores/mixin.ts | 27 +++++++++++++--------------
 1 file changed, 13 insertions(+), 14 deletions(-)

diff --git a/src/stores/mixin.ts b/src/stores/mixin.ts
index c7650da..421dbe6 100644
--- a/src/stores/mixin.ts
+++ b/src/stores/mixin.ts
@@ -225,7 +225,13 @@ export const useCounterMixin = defineStore("mixin", () => {
   }
 
   function monthYear2Thai(month: number, year: number, isFullMonth = false) {
-    const date = new Date(`${year}-${month + 1}-1`);
+    if (
+      month < 0 ||
+      month > 11 ||
+      !Number.isFinite(month) ||
+      !Number.isFinite(year)
+    )
+      return "";
     const fullMonthThai = [
       "มกราคม",
       "กุมภาพันธ์",
@@ -254,19 +260,12 @@ export const useCounterMixin = defineStore("mixin", () => {
       "พ.ย.",
       "ธ.ค.",
     ];
-    let dstYear = 0;
-    if (date.getFullYear() > 2500) {
-      dstYear = date.getFullYear();
-    } else {
-      dstYear = date.getFullYear() + 543;
-    }
-    let dstMonth = "";
-    if (isFullMonth) {
-      dstMonth = fullMonthThai[date.getMonth()];
-    } else {
-      dstMonth = abbrMonthThai[date.getMonth()];
-    }
-    return dstMonth + " " + dstYear;
+
+    // assume year is in BE if > 2500
+    let dstYear = year > 2500 ? year : year + 543;
+    // month is already 0-based
+    let dstMonth = isFullMonth ? fullMonthThai[month] : abbrMonthThai[month];
+    return `${dstMonth} ${dstYear}`;
   }
 
   function dateToISO(date: Date) {