From 7c028253be355f22ab4a1d115acb644d01edc138 Mon Sep 17 00:00:00 2001
From: Colin Rotherham <work@colinr.com>
Date: Thu, 29 Jun 2023 07:44:02 +0100
Subject: [PATCH] Change GitHub release JavaScript to ES modules

---
 packages/govuk-frontend/rollup.release.config.mjs   | 13 ++++---------
 .../govuk-frontend/tasks/build/release.test.mjs     |  2 +-
 2 files changed, 5 insertions(+), 10 deletions(-)

diff --git a/packages/govuk-frontend/rollup.release.config.mjs b/packages/govuk-frontend/rollup.release.config.mjs
index 8537eb4a19..dad643d30c 100644
--- a/packages/govuk-frontend/rollup.release.config.mjs
+++ b/packages/govuk-frontend/rollup.release.config.mjs
@@ -2,14 +2,13 @@ import replace from '@rollup/plugin-replace'
 import terser from '@rollup/plugin-terser'
 import * as GOVUKFrontend from 'govuk-frontend/src/govuk/all.mjs'
 import { pkg } from 'govuk-frontend-config'
-import { componentPathToModuleName } from 'govuk-frontend-lib/names'
 import { defineConfig } from 'rollup'
 
 /**
  * Rollup config for GitHub release
  *
- * Universal Module Definition (UMD) bundle for browser <script>
- * `window` globals and compatibility with CommonJS and AMD `require()`
+ * ECMAScript (ES) module bundles for browser <script type="module">
+ * or using `import` for modern browsers and Node.js scripts
  */
 export default defineConfig(({ i: input }) => ({
   input,
@@ -19,7 +18,7 @@ export default defineConfig(({ i: input }) => ({
    */
   output: {
     compact: true,
-    format: 'umd',
+    format: 'es',
 
     // Bundled modules
     preserveModules: false,
@@ -41,11 +40,7 @@ export default defineConfig(({ i: input }) => ({
         // Compatibility workarounds
         safari10: true
       })
-    ],
-
-    // Components are given names (e.g window.GOVUKFrontend.Accordion)
-    amd: { id: componentPathToModuleName(input) },
-    name: componentPathToModuleName(input)
+    ]
   },
 
   /**
diff --git a/packages/govuk-frontend/tasks/build/release.test.mjs b/packages/govuk-frontend/tasks/build/release.test.mjs
index 01801c81d0..331cfcba3e 100644
--- a/packages/govuk-frontend/tasks/build/release.test.mjs
+++ b/packages/govuk-frontend/tasks/build/release.test.mjs
@@ -79,7 +79,7 @@ describe('dist/', () => {
     })
 
     it('should contain correct version number', () => {
-      expect(javascript).toContain(`.version="${pkg.version}"`)
+      expect(javascript).toContain(`const version="${pkg.version}"`)
     })
 
     it('should contain source mapping URL', () => {