From 3fe99cee603007726ecce4be8ae57bd32962d35c Mon Sep 17 00:00:00 2001
From: Colin Rotherham <work@colinr.com>
Date: Thu, 6 Jul 2023 09:20:57 +0100
Subject: [PATCH 1/3] =?UTF-8?q?Ensure=20package=20export=20Node.js=20v12.1?=
 =?UTF-8?q?8=20test=20doesn=E2=80=99t=20use=20`--conditions`?=
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We’re likely to add more package export matrix combinations in future

But the flag `--conditions` was only added in Node.js v12.19.0

So rather than do the hard job to “opt out” Node.js 12.18.0 from _every_ incompatible matrix combination, let’s just “opt in” to the package export tests we know will run
---
 .github/workflows/tests.yml | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index 6855af4b45..9e5498e176 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -241,17 +241,16 @@ jobs:
 
       matrix:
         node-version:
-          - 12.18 # Node.js 12.18 uses package exports with trailing slashes
-          - 12 # But Node.js 12.20+ uses package exports with subpath patterns
-          - 18
+          - 12 # Node.js 12.20+ uses package exports with subpath patterns
+          - 18 # Node.js 17+ cannot use package exports with trailing slashes
 
         conditions:
           - require
           - import
 
-        exclude:
-          - conditions: import
-            node-version: 12.18
+        include:
+          - conditions: require
+            node-version: 12.18 # Node.js 12.18 uses package exports with trailing slashes
 
     env:
       # Node.js conditions override from "require" to "import" etc

From b0211992c1b1ed9026ec759a15e960ed040877f1 Mon Sep 17 00:00:00 2001
From: Colin Rotherham <work@colinr.com>
Date: Thu, 6 Jul 2023 09:24:00 +0100
Subject: [PATCH 2/3] Ensure package export tests can support multiple
 conditions

We may want to add `[browser]` and `[browser, import]` to differentiate exports for Browserify and webpack v4 in future
---
 .github/workflows/tests.yml | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index 9e5498e176..2cfbd54f4a 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -232,7 +232,7 @@ jobs:
         run: ${{ matrix.task.run }}
 
   package:
-    name: Export ${{ matrix.conditions }}, Node.js ${{ matrix.node-version }}
+    name: Export ${{ join(matrix.conditions, ' ') || 'require' }}, Node.js ${{ matrix.node-version }}
     runs-on: ubuntu-latest
     needs: [install, build]
 
@@ -245,17 +245,17 @@ jobs:
           - 18 # Node.js 17+ cannot use package exports with trailing slashes
 
         conditions:
-          - require
-          - import
+          - [require]
+          - [import]
 
         include:
-          - conditions: require
+          - conditions: []
             node-version: 12.18 # Node.js 12.18 uses package exports with trailing slashes
 
     env:
       # Node.js conditions override from "require" to "import" etc
       # https://nodejs.org/api/cli.html#-c-condition---conditionscondition
-      FLAGS: ${{ matrix.conditions != 'require' && format(' --conditions {0}', matrix.conditions) || '' }}
+      FLAGS: ${{ matrix.conditions[0] != null && format(' --conditions {0}', join(matrix.conditions, ' --conditions ')) || '' }}
 
     steps:
       - name: Checkout

From 71b4813ce53e3ec675617631989955b316529828 Mon Sep 17 00:00:00 2001
From: Colin Rotherham <work@colinr.com>
Date: Wed, 5 Jul 2023 14:44:58 +0100
Subject: [PATCH 3/3] Add bundled-only package exports for `"browser"`
 condition

Update package exports and add `[browser]` and `[browser, import]` conditions to differentiate exports for Browserify and webpack v4
---
 .github/workflows/tests.yml          | 2 ++
 packages/govuk-frontend/package.json | 6 ++++++
 2 files changed, 8 insertions(+)

diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index 2cfbd54f4a..eb920e060a 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -247,6 +247,8 @@ jobs:
         conditions:
           - [require]
           - [import]
+          - [browser, require]
+          - [browser, import]
 
         include:
           - conditions: []
diff --git a/packages/govuk-frontend/package.json b/packages/govuk-frontend/package.json
index 5ccbe51678..d527c4a5a2 100644
--- a/packages/govuk-frontend/package.json
+++ b/packages/govuk-frontend/package.json
@@ -13,6 +13,12 @@
   ],
   "exports": {
     ".": {
+      "browser": {
+        "sass": "./dist/govuk/all.scss",
+        "import": "./dist/govuk/all.bundle.mjs",
+        "require": "./dist/govuk/all.bundle.js",
+        "default": "./dist/govuk/all.bundle.js"
+      },
       "sass": "./dist/govuk/all.scss",
       "import": "./dist/govuk/all.mjs",
       "require": "./dist/govuk/all.bundle.js",