From 917c3c81dfd7924f290e457e84cf7321d7a90042 Mon Sep 17 00:00:00 2001
From: abhijeet117 <abhijeetkumarsah92@gmail.com>
Date: Mon, 24 Aug 2026 00:45:04 +0530
Subject: [PATCH] fix(isISO8601): validate signed ordinal dates in strict mode

---
 src/lib/isISO8601.js    |  6 +++---
 test/validators.test.js | 16 ++++++++++++++++
 2 files changed, 19 insertions(+), 3 deletions(-)

diff --git a/src/lib/isISO8601.js b/src/lib/isISO8601.js
index 6eea9ae27..a8cfbd29f 100644
--- a/src/lib/isISO8601.js
+++ b/src/lib/isISO8601.js
@@ -11,10 +11,10 @@ const isValidDate = (str) => {
   // this check is meant to catch invalid dates
   // like 2009-02-31
   // first check for ordinal dates
-  const ordinalMatch = str.match(/^(\d{4})-?(\d{3})([ T]{1}\.*|$)/);
+  const ordinalMatch = str.match(/^([+-]?)(\d{4})-?(\d{3})([ T]{1}\.*|$)/);
   if (ordinalMatch) {
-    const oYear = Number(ordinalMatch[1]);
-    const oDay = Number(ordinalMatch[2]);
+    const oYear = Number(ordinalMatch[2]);
+    const oDay = Number(ordinalMatch[3]);
     // if is leap year
     if ((oYear % 4 === 0 && oYear % 100 !== 0) || oYear % 400 === 0) return oDay <= 366;
     return oDay <= 365;
diff --git a/test/validators.test.js b/test/validators.test.js
index 98d2a12ff..ab271e946 100644
--- a/test/validators.test.js
+++ b/test/validators.test.js
@@ -12453,6 +12453,22 @@ describe('Validators', () => {
     });
   });
 
+  it('should validate ISO 8601 dates, validating signed ordinal dates in strict mode', () => {
+    test({
+      validator: 'isISO8601',
+      args: [
+        { strict: true },
+      ],
+      valid: [
+        '+2009-145',
+        '+2020-366',
+      ],
+      invalid: [
+        '+2009-366',
+      ],
+    });
+  });
+
   it('should validate ISO 8601 dates, with strictSeparator = true', () => {
     test({
       validator: 'isISO8601',