[5.0] ESM importmap support

build/build-modules-js/init/localise-packages.es6.js

@@ -7,6 +7,25 @@ const { tinyMCE } = require('./exemptions/tinymce.es6.js');
 
 const RootPath = process.cwd();
 
+/**
+ * Find full path for package file.
+ * Replacement for require.resolve(), as it is broken for packages with "exports" property.
+ *
+ * @param {string} relativePath Relative path to the file to resolve, in format packageName/file-name.js
+ * @returns {string|boolean}
+ */
+const resolvePackageFile = (relativePath) => {
+  for (let i = 0, l = module.paths.length; i < l; i += 1) {
+    const path = module.paths[i];
+    const fullPath = `${path}/${relativePath}`;
+    if (existsSync(fullPath)) {
+      return fullPath;
+    }
+  }
+
+  return false;
+};
+
 /**
  *
  * @param {object} files    the object of files map, eg {"src.js": "js/src.js"}
@@ -39,7 +58,7 @@ const copyFilesTo = async (files, srcDir, destDir) => {
  */
 const resolvePackage = async (vendor, packageName, mediaVendorPath, options, registry) => {
   const vendorName = vendor.name || packageName;
-  const modulePathJson = require.resolve(`${packageName}/package.json`);
+  const modulePathJson = resolvePackageFile(`${packageName}/package.json`);
   const modulePathRoot = dirname(modulePathJson);
   // eslint-disable-next-line global-require, import/no-dynamic-require
   const moduleOptions = require(modulePathJson);

build/build-modules-js/init/minify-vendor.es6.js

@@ -11,6 +11,7 @@ const folders = [
   'media/vendor/codemirror',
   'media/vendor/debugbar',
   'media/vendor/diff/js',
+  'media/vendor/es-module-shims/js',
   'media/vendor/qrcode/js',
   'media/vendor/short-and-sweet/js',
   'media/vendor/webcomponentsjs/js',

build/build-modules-js/settings.json

@@ -341,6 +341,24 @@
         "dependencies": [],
         "licenseFilename": "license"
       },
+      "es-module-shims": {
+        "name": "es-module-shims",
+        "js": {
+          "dist/es-module-shims.js": "js/es-module-shims.js"
+        },
+        "provideAssets": [
+          {
+            "name": "es-module-shims",
+            "type": "script",
+            "uri": "es-module-shims.min.js",
+            "attributes": {
+              "async": true
+            }
+          }
+        ],
+        "dependencies": [],
+        "licenseFilename": "LICENSE"
+      },
       "focus-visible": {
         "name": "focus-visible",
         "js": {

libraries/src/Document/Renderer/Html/ScriptsRenderer.php

@@ -56,6 +56,9 @@ public function render($head, $params = [], $content = null)
         $inlineAssets   = $wam->filterOutInlineAssets($assets);
         $inlineRelation = $wam->getInlineRelation($inlineAssets);
 
+        // Generate importmap first
+        $buffer .= $this->renderImportmap($assets);
+
         // Merge with existing scripts, for rendering
         $assets = array_merge(array_values($assets), $this->_doc->_scripts);
 
@@ -138,7 +141,7 @@ private function renderElement($item): string
         $src    = $asset ? $asset->getUri() : ($item['src'] ?? '');
 
         // Make sure we have a src, and it not already rendered
-        if (!$src || !empty($this->renderedSrc[$src]) || ($asset && $asset->getOption('webcomponent'))) {
+        if (!$src || !empty($this->renderedSrc[$src])) {
             return '';
         }
 
@@ -320,4 +323,77 @@ private function renderAttributes(array $attributes): string
 
         return $buffer;
     }
+
+    /**
+     * Renders ESM importmap element
+     *
+     * @param   WebAssetItemInterface[]  $assets  The assets list
+     *
+     * @return  string  The attributes string
+     *
+     * @since   __DEPLOY_VERSION__
+     */
+    private function renderImportmap(array &$assets)
+    {
+        $buffer       = '';
+        $importmap    = ['imports' => []];
+        $tab          = $this->_doc->_getTab();
+        $mediaVersion = $this->_doc->getMediaVersion();
+
+        // Collect a modules for the map
+        foreach ($assets as $k => $item) {
+            // Only importmap:true can be mapped
+            if (!$item->getOption('importmap')) {
+                continue;
+            }
+
+            $esmName  = $item->getOption('importmapName') ?: $item->getName();
+            $esmScope = $item->getOption('importmapScope');
+            $version  = $item->getVersion();
+            $src      = $item->getUri();
+
+            if (!$src) {
+                continue;
+            }
+
+            // Check if script uses media version.
+            if ($version && !str_contains($src, '?') && !str_ends_with($src, '/') && ($mediaVersion || $version !== 'auto')) {
+                $src .= '?' . ($version === 'auto' ? $mediaVersion : $version);
+            }
+
+            if (!$esmScope) {
+                $importmap['imports'][$esmName] = $src;
+            } else {
+                $importmap['scopes'][$esmScope][$esmName] = $src;
+            }
+
+            // Remove the item from list of assets after it were added to the map.
+            unset($assets[$k]);
+        }
+
+        if (!empty($importmap['imports'])) {
+            // Add polyfill when exists
+            if (!empty($assets['es-module-shims'])) {
+                $buffer .= $this->renderElement($assets['es-module-shims']);
+            }
+
+            // Render importmap
+            $jsonImports = json_encode($importmap, JDEBUG ? JSON_PRETTY_PRINT | JSON_UNESCAPED_SLASHES : JSON_UNESCAPED_SLASHES);
+            $attribs     = ['type' => 'importmap'];
+
+            // Add "nonce" attribute if exist
+            if ($this->_doc->cspNonce && !is_null($this->_doc->cspNonce)) {
+                $attribs['nonce'] = $this->_doc->cspNonce;
+            }
+
+            $buffer .= $tab . '<script';
+            $buffer .= $this->renderAttributes($attribs);
+            $buffer .= '>' . $jsonImports . '</script>';
+        }
+
+        // Remove polyfill for "importmap" from assets list
+        unset($assets['es-module-shims']);
+
+        return $buffer;
+    }
 }

libraries/src/WebAsset/WebAssetItem.php

@@ -10,6 +10,7 @@
 namespace Joomla\CMS\WebAsset;
 
 use Joomla\CMS\HTML\HTMLHelper;
+use Joomla\CMS\Uri\Uri;
 
 // phpcs:disable PSR1.Files.SideEffects
 \defined('_JEXEC') or die;
@@ -175,6 +176,10 @@ public function getUri($resolvePath = true): string
                     $path = $this->resolvePath($path, 'stylesheet');
                     break;
                 default:
+                    // Asset for the ES modules may give us a folder for ESM import map
+                    if (str_ends_with($path, '/') && !str_starts_with($path, '.')) {
+                        $path = Uri::root(true) . '/' . $path;
+                    }
                     break;
             }
         }

package.json

@@ -52,6 +52,7 @@
     "diff": "^5.1.0",
     "dotenv": "^16.0.3",
     "dragula": "^3.7.3",
+    "es-module-shims": "^1.7.3",
     "focus-visible": "^5.2.0",
     "hotkeys-js": "^3.10.2",
     "joomla-ui-custom-elements": "^0.2.0",