From 1bc2a6ef7655d9f1139dcb2d96af9552563676d3 Mon Sep 17 00:00:00 2001
From: Cory LaViska <cory@abeautifulsite.net>
Date: Thu, 16 Feb 2023 12:15:59 -0500
Subject: [PATCH] expose rel; fixes #1200

---
 docs/resources/changelog.md          |  1 +
 src/components/button/button.test.ts | 24 ++++++++++++++++++++++++
 src/components/button/button.ts      | 10 +++++++++-
 3 files changed, 34 insertions(+), 1 deletion(-)

diff --git a/docs/resources/changelog.md b/docs/resources/changelog.md
index 61a5f48a..4ca38065 100644
--- a/docs/resources/changelog.md
+++ b/docs/resources/changelog.md
@@ -12,6 +12,7 @@ New versions of Shoelace are released as-needed and generally occur when a criti
 - Added the `focus()` and `blur()` methods to `<sl-color-picker>`
 - Added the `sl-invalid` event to all form controls to enable custom validation logic [#1167](https://github.com/shoelace-style/shoelace/pull/1167)
 - Added `validity` and `validationMessage` properties to all form controls [#1167](https://github.com/shoelace-style/shoelace/pull/1167)
+- Added the `rel` attribute to `<sl-button>` to allow users to create button links that point to specific targets [#1200](https://github.com/shoelace-style/shoelace/issues/1200)
 - Fixed a bug in `<sl-animated-image>` where the play and pause buttons were transposed [#1147](https://github.com/shoelace-style/shoelace/issues/1147)
 - Fixed a bug that prevented `web-types.json` from being generated [#1154](https://github.com/shoelace-style/shoelace/discussions/1154)
 - Fixed a bug in `<sl-color-picker>` that prevented `sl-change` and `sl-input` from emitting when using the eye dropper [#1157](https://github.com/shoelace-style/shoelace/issues/1157)
diff --git a/src/components/button/button.test.ts b/src/components/button/button.test.ts
index cc881fa2..16f155b5 100644
--- a/src/components/button/button.test.ts
+++ b/src/components/button/button.test.ts
@@ -117,6 +117,30 @@ describe('<sl-button>', () => {
       expect(el.shadowRoot!.querySelector('a')).to.exist;
       expect(el.shadowRoot!.querySelector('button')).not.to.exist;
     });
+
+    it('should render a link with rel="noreferrer noopener" when target is set and rel is not', async () => {
+      const el = await fixture<SlButton>(
+        html` <sl-button href="https://example.com/" target="_blank">Link</sl-button> `
+      );
+      const link = el.shadowRoot!.querySelector('a')!;
+      expect(link?.getAttribute('rel')).to.equal('noreferrer noopener');
+    });
+
+    it('should render a link with rel="" when a target is provided and rel is empty', async () => {
+      const el = await fixture<SlButton>(
+        html` <sl-button href="https://example.com/" target="_blank" rel="">Link</sl-button> `
+      );
+      const link = el.shadowRoot!.querySelector('a')!;
+      expect(link?.getAttribute('rel')).to.equal('');
+    });
+
+    it(`should render a link with a custom rel when a custom rel is provided`, async () => {
+      const el = await fixture<SlButton>(
+        html` <sl-button href="https://example.com/" target="_blank" rel="1">Link</sl-button> `
+      );
+      const link = el.shadowRoot!.querySelector('a')!;
+      expect(link?.getAttribute('rel')).to.equal('1');
+    });
   });
 
   describe('when submitting a form', () => {
diff --git a/src/components/button/button.ts b/src/components/button/button.ts
index 1744ea57..bbf5f4de 100644
--- a/src/components/button/button.ts
+++ b/src/components/button/button.ts
@@ -116,6 +116,14 @@ export default class SlButton extends ShoelaceElement implements ShoelaceFormCon
   /** Tells the browser where to open the link. Only used when `href` is present. */
   @property() target: '_blank' | '_parent' | '_self' | '_top';
 
+  /**
+   * When using `href`, this attribute will map to the underlying link's `rel` attribute. Unlike regular links, the
+   * default is `noreferrer noopener` to prevent security exploits. However, if you're using `target` to point to a
+   * specific tab/window, this will prevent that from working correctly. You can remove or change the default value by
+   * setting the attribute to an empty string or a value of your choice, respectively.
+   */
+  @property() rel = 'noreferrer noopener';
+
   /** Tells the browser to download the linked file as this filename. Only used when `href` is present. */
   @property() download?: string;
 
@@ -308,7 +316,7 @@ export default class SlButton extends ShoelaceElement implements ShoelaceFormCon
         href=${ifDefined(isLink ? this.href : undefined)}
         target=${ifDefined(isLink ? this.target : undefined)}
         download=${ifDefined(isLink ? this.download : undefined)}
-        rel=${ifDefined(isLink && this.target ? 'noreferrer noopener' : undefined)}
+        rel=${ifDefined(isLink ? this.rel : undefined)}
         role=${ifDefined(isLink ? undefined : 'button')}
         aria-disabled=${this.disabled ? 'true' : 'false'}
         tabindex=${this.disabled ? '-1' : '0'}