PLATUI-2829: Do not remove back link when referrer is empty

CHANGELOG.md

@@ -7,6 +7,12 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 
 ## [Unreleased]
 
+## [6.12.0] - 2024-03-26
+
+### Changed
+
+- Retain the back link even when the referrer is empty
+
 ## [6.11.0] - 2024-03-25
 
 ### Changed

package.json

@@ -1,6 +1,6 @@
 {
   "name": "hmrc-frontend",
-  "version": "6.11.0",
+  "version": "6.12.0",
   "description": "Design patterns for HMRC frontends",
   "scripts": {
     "start": "gulp dev",

src/components/back-link-helper/back-link-helper.js

@@ -5,13 +5,27 @@ function BackLinkHelper($module, window, document) {
 }
 
 BackLinkHelper.prototype.init = function init() {
+  const isReferrerExternal = () => {
+    // If there is no referrer, consider it on the same domain
+    if (!this.document.referrer) {
+      return false;
+    }
+
+    try {
+      const currentDomain = new URL(this.window.location.href).hostname;
+      const referrerDomain = new URL(this.document.referrer).hostname;
+
+      // Check if the referrer is not the same as the current domain
+      return currentDomain !== referrerDomain;
+    } catch (err) {
+      return false;
+    }
+  };
+
   // do nothing if History API is absent
   if (this.window.history) {
-    // store referrer value to cater for IE
-    const docReferrer = this.document.referrer;
-
-    // hide the backlink if the referrer is on a different domain or the referrer is not set
-    if (docReferrer === '' || docReferrer.indexOf(this.window.location.host) === -1) {
+    // hide the backlink if the referrer is on a different domain
+    if (isReferrerExternal()) {
       this.$module.classList.add('hmrc-hidden-backlink');
     } else {
       // prevent resubmit warning

src/components/back-link-helper/back-link-helper.test.js

@@ -71,11 +71,11 @@ describe('/components/back-link-helper', () => {
       expect(mockWindow.history.back).toHaveBeenCalled();
     });
 
-    it('adds .hmrc-hidden-backlink class to backlink when document referer is empty', () => {
+    it('does not add .hmrc-hidden-backlink class to backlink when document referer is empty', () => {
       const sut = new BackLinkHelper(mockAnchorTag, mockWindow, { referrer: '' });
       sut.init();
 
-      expect(mockAnchorTag.classList.add.mock.calls[0][0]).toBe('hmrc-hidden-backlink');
+      expect(mockAnchorTag.classList.add.mock.calls).toHaveLength(0);
     });
 
     it('adds .hmrc-hidden-backlink class to backlink if document referer is on a different domain', () => {