From ae2267caf5f462e5520b5c791609b43210bdc487 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Max=20=F0=9F=91=A8=F0=9F=8F=BD=E2=80=8D=F0=9F=92=BB=20Copl?=
 =?UTF-8?q?an?= <mchcopl@gmail.com>
Date: Mon, 2 Feb 2026 11:47:15 -0800
Subject: [PATCH] fix: teach <Helmet> to accept base tag with only 'target'
 attribute

From the spec:
> The `base` element must have an `href` attribute, a `target` attribute, or both.
---
 __tests__/api/base.test.tsx    | 37 ++++++++++++++++++++--
 __tests__/server/base.test.tsx | 58 ++++++++++++++++++++++++++++++++++
 src/constants.ts               |  1 +
 src/utils.ts                   |  2 +-
 4 files changed, 94 insertions(+), 4 deletions(-)

diff --git a/__tests__/api/base.test.tsx b/__tests__/api/base.test.tsx
index e962e4a7..34953a9a 100644
--- a/__tests__/api/base.test.tsx
+++ b/__tests__/api/base.test.tsx
@@ -30,8 +30,21 @@ describe('base tag', () => {
       expect(existingTags).toHaveLength(0);
     });
 
-    it('tags without \'href\' are not accepted', () => {
-      renderClient(<Helmet base={{ property: 'won\'t work' }} />);
+    it("tags with only 'target' are accepted", () => {
+      renderClient(<Helmet base={{ target: '_blank' }} />);
+      const existingTags = [...document.head.querySelectorAll(`base[${HELMET_ATTRIBUTE}]`)];
+
+      expect(existingTags).toBeDefined();
+      expect(existingTags).toHaveLength(1);
+      const firstTag = existingTags[0]!;
+      expect(firstTag).toBeInstanceOf(Element);
+      expect(firstTag.getAttribute).toBeDefined();
+      expect(firstTag).toHaveAttribute('target', '_blank');
+      expect(firstTag).not.toHaveAttribute('href');
+    });
+
+    it("tags without 'href' or 'target' are not accepted", () => {
+      renderClient(<Helmet base={{ property: "won't work" }} />);
       const existingTags = document.head.querySelectorAll(`base[${HELMET_ATTRIBUTE}]`);
 
       expect(existingTags).toBeDefined();
@@ -97,7 +110,25 @@ describe('base tag', () => {
       expect(existingTags).toHaveLength(0);
     });
 
-    it('tags without \'href\' are not accepted', () => {
+    it("tags with only 'target' are accepted", () => {
+      renderClient(
+        <Helmet>
+          <base target="_blank" />
+        </Helmet>,
+      );
+
+      const existingTags = [...document.head.querySelectorAll(`base[${HELMET_ATTRIBUTE}]`)];
+
+      expect(existingTags).toBeDefined();
+      expect(existingTags).toHaveLength(1);
+      const firstTag = existingTags[0]!;
+      expect(firstTag).toBeInstanceOf(Element);
+      expect(firstTag.getAttribute).toBeDefined();
+      expect(firstTag).toHaveAttribute('target', '_blank');
+      expect(firstTag).not.toHaveAttribute('href');
+    });
+
+    it("tags without 'href' or 'target' are not accepted", () => {
       /* eslint-disable react/no-unknown-property */
       renderClient(
         <Helmet>
diff --git a/__tests__/server/base.test.tsx b/__tests__/server/base.test.tsx
index 8ffd818e..7deede99 100644
--- a/__tests__/server/base.test.tsx
+++ b/__tests__/server/base.test.tsx
@@ -35,6 +35,30 @@ describe('server', () => {
       expect(head?.base.toString).toBeDefined();
       expect(head?.base.toString()).toMatchSnapshot();
     });
+
+    it("renders base tag with only 'target' as React component", () => {
+      const head = renderContextServer(<Helmet base={{ target: '_blank' }} />);
+
+      expect(head?.base).toBeDefined();
+      expect(head?.base.toComponent).toBeDefined();
+
+      const baseComponent = head?.base.toComponent();
+
+      expect(baseComponent).toStrictEqual(isArray);
+      expect(baseComponent).toHaveLength(1);
+
+      const markup = renderToStaticMarkup(baseComponent);
+      expect(markup).toContain('target="_blank"');
+      expect(markup).not.toContain('href=');
+    });
+
+    it("renders base tag with only 'target' as string", () => {
+      const head = renderContextServer(<Helmet base={{ target: '_blank' }} />);
+      expect(head?.base).toBeDefined();
+      expect(head?.base.toString).toBeDefined();
+      expect(head?.base.toString()).toContain('target="_blank"');
+      expect(head?.base.toString()).not.toContain('href=');
+    });
   });
 
   describe('Declarative API', () => {
@@ -73,5 +97,39 @@ describe('server', () => {
       expect(head!.base.toString).toBeDefined();
       expect(head?.base.toString()).toMatchSnapshot();
     });
+
+    it("renders base tag with only 'target' as React component", () => {
+      const head = renderContextServer(
+        <Helmet>
+          <base target="_blank" />
+        </Helmet>,
+      );
+
+      expect(head?.base).toBeDefined();
+      expect(head?.base.toComponent).toBeDefined();
+
+      const baseComponent = head?.base.toComponent();
+
+      expect(baseComponent).toStrictEqual(isArray);
+      expect(baseComponent).toHaveLength(1);
+
+      const markup = renderToStaticMarkup(baseComponent);
+
+      expect(markup).toContain('target="_blank"');
+      expect(markup).not.toContain('href=');
+    });
+
+    it("renders base tag with only 'target' as string", () => {
+      const head = renderContextServer(
+        <Helmet>
+          <base target="_blank" />
+        </Helmet>,
+      );
+
+      expect(head?.base).toBeDefined();
+      expect(head?.base.toString).toBeDefined();
+      expect(head?.base.toString()).toContain('target="_blank"');
+      expect(head?.base.toString()).not.toContain('href=');
+    });
   });
 });
diff --git a/src/constants.ts b/src/constants.ts
index e7106020..d56e6b29 100644
--- a/src/constants.ts
+++ b/src/constants.ts
@@ -9,6 +9,7 @@ export enum TAG_PROPERTIES {
   PROPERTY = 'property',
   REL = 'rel',
   SRC = 'src',
+  TARGET = 'target',
 }
 
 export enum ATTRIBUTE_NAMES {
diff --git a/src/utils.ts b/src/utils.ts
index 7e638fa7..8c6e8326 100644
--- a/src/utils.ts
+++ b/src/utils.ts
@@ -103,7 +103,7 @@ export function aggregateBaseProps(
 ): BaseProps | undefined {
   for (let i = props.length - 1; i >= 0; --i) {
     const res = props[i]![1].base;
-    if (res?.href) return res;
+    if (res?.href || res?.target) return res;
   }
   return undefined;
 }