Add a Babel transform loader to ESM in the global server

This ensures we can load JSX in there for SSR.

Author: sebmarkbage

fixtures/flight/loader/global.js

@@ -0,0 +1,52 @@
+import babel from '@babel/core';
+
+const babelOptions = {
+  babelrc: false,
+  ignore: [/\/(build|node_modules)\//],
+  plugins: [
+    '@babel/plugin-syntax-import-meta',
+    '@babel/plugin-transform-react-jsx',
+  ],
+};
+
+export async function load(url, context, defaultLoad) {
+  const {format} = context;
+  const result = await defaultLoad(url, context, defaultLoad);
+  if (result.format === 'module') {
+    const opt = Object.assign({filename: url}, babelOptions);
+    const newResult = await babel.transformAsync(result.source, opt);
+    if (!newResult) {
+      if (typeof result.source === 'string') {
+        return result;
+      }
+      return {
+        source: Buffer.from(result.source).toString('utf8'),
+        format: 'module',
+      };
+    }
+    return {source: newResult.code, format: 'module'};
+  }
+  return defaultLoad(url, context, defaultLoad);
+}
+
+async function babelTransformSource(source, context, defaultTransformSource) {
+  const {format} = context;
+  if (format === 'module') {
+    const opt = Object.assign({filename: context.url}, babelOptions);
+    const newResult = await babel.transformAsync(source, opt);
+    if (!newResult) {
+      if (typeof source === 'string') {
+        return {source};
+      }
+      return {
+        source: Buffer.from(source).toString('utf8'),
+      };
+    }
+    return {source: newResult.code};
+  }
+  return defaultTransformSource(source, context, defaultTransformSource);
+}
+
+export const transformSource =
+  process.version < 'v16' ? babelTransformSource : undefined;
+export const getSource = process.version < 'v16' ? getSourceImpl : undefined;

fixtures/flight/loader/index.js renamed to fixtures/flight/loader/region.js

@@ -65,11 +65,11 @@
     "predev": "cp -r ../../build/oss-experimental/* ./node_modules/",
     "prebuild": "cp -r ../../build/oss-experimental/* ./node_modules/",
     "dev": "concurrently \"npm run dev:region\" \"npm run dev:global\"",
-    "dev:global": "NODE_ENV=development BUILD_PATH=dist node server/global",
-    "dev:region": "NODE_ENV=development BUILD_PATH=dist nodemon --watch src --watch dist -- --experimental-loader ./loader/index.js --conditions=react-server server/region",
+    "dev:global": "NODE_ENV=development BUILD_PATH=dist node --experimental-loader ./loader/global.js server/global",
+    "dev:region": "NODE_ENV=development BUILD_PATH=dist nodemon --watch src --watch dist -- --experimental-loader ./loader/region.js --conditions=react-server server/region",
     "start": "node scripts/build.js && concurrently \"npm run start:region\" \"npm run start:global\"",
-    "start:global": "NODE_ENV=production node server/global",
-    "start:region": "NODE_ENV=production node --experimental-loader ./loader/index.js --conditions=react-server server/region",
+    "start:global": "NODE_ENV=production node --experimental-loader ./loader/global.js server/global",
+    "start:region": "NODE_ENV=production node --experimental-loader ./loader/region.js --conditions=react-server server/region",
     "build": "node scripts/build.js",
     "test": "node scripts/test.js --env=jsdom"
   },