esm: allow configuring default package type

configure.py

@@ -641,6 +641,12 @@
     default=False,
     help='node will load builtin modules from disk instead of from binary')
 
+parser.add_option('--default-package-type',
+    action='store',
+    dest='node_default_package_type',
+    default=False,
+    help='node will treat files outside of package boundaries as this type')
+
 # Create compile_commands.json in out/Debug and out/Release.
 parser.add_option('-C',
     action='store_true',
@@ -1185,6 +1191,11 @@ def configure_node(o):
     print('Warning! Loading builtin modules from disk is for development')
     o['variables']['node_builtin_modules_path'] = options.node_builtin_modules_path
 
+  if options.node_default_package_type:
+    if not ( options.node_default_package_type in ['module', 'commonjs'] ):
+      raise Exception('--default-package-type must be either "module" or "commonjs"');
+    o['variables']['node_default_package_type'] = options.node_default_package_type
+
 def configure_napi(output):
   version = getnapibuildversion.get_napi_version()
   output['variables']['napi_build_version'] = version

lib/internal/modules/esm/get_format.js

@@ -10,6 +10,7 @@ const experimentalWasmModules = getOptionValue('--experimental-wasm-modules');
 const { getPackageType } = require('internal/modules/esm/resolve');
 const { URL, fileURLToPath } = require('internal/url');
 const { ERR_UNKNOWN_FILE_EXTENSION } = require('internal/errors').codes;
+const { defaultPackageType } = internalBinding('config');
 
 const extensionFormatMap = {
   '__proto__': null,
@@ -51,7 +52,8 @@ function defaultGetFormat(url, context, defaultGetFormatUnused) {
     const ext = extname(parsed.pathname);
     let format;
     if (ext === '.js') {
-      format = getPackageType(parsed.href) === 'module' ? 'module' : 'commonjs';
+      const type = getPackageType(parsed.href);
+      format = type !== 'none' ? type : defaultPackageType;
     } else {
       format = extensionFormatMap[ext];
     }

lib/internal/modules/run_main.js

@@ -4,6 +4,7 @@ const CJSLoader = require('internal/modules/cjs/loader');
 const { Module, toRealPath, readPackageScope } = CJSLoader;
 const { getOptionValue } = require('internal/options');
 const path = require('path');
+const { defaultPackageType } = internalBinding('config');
 
 function resolveMainPath(main) {
   // Note extension resolution for the main entry point can be deprecated in a
@@ -33,8 +34,11 @@ function shouldUseESMLoader(mainPath) {
     return true;
   if (!mainPath || mainPath.endsWith('.cjs'))
     return false;
-  const pkg = readPackageScope(mainPath);
-  return pkg && pkg.data.type === 'module';
+  const pkgType = readPackageScope(mainPath)?.data?.type ?? 'none';
+  return pkgType === 'module' || (
+    pkgType === 'none' &&
+    defaultPackageType === 'module'
+  );
 }
 
 function runMainESM(mainPath) {

node.gyp

@@ -26,6 +26,7 @@
     'node_lib_target_name%': 'libnode',
     'node_intermediate_lib_type%': 'static_library',
     'node_builtin_modules_path%': '',
+    'node_default_package_type%': '',
     'library_files': [
       'lib/internal/bootstrap/environment.js',
       'lib/internal/bootstrap/loaders.js',
@@ -748,6 +749,9 @@
         [ 'node_builtin_modules_path!=""', {
           'defines': [ 'NODE_BUILTIN_MODULES_PATH="<(node_builtin_modules_path)"' ]
         }],
+        [ 'node_default_package_type!=""', {
+          'defines': [ 'NODE_DEFAULT_PACKAGE_TYPE="<(node_default_package_type)"' ]
+        }],
         [ 'node_shared=="true"', {
           'sources': [
             'src/node_snapshot_stub.cc',

src/node_config.cc

@@ -13,6 +13,7 @@ using v8::Isolate;
 using v8::Local;
 using v8::Number;
 using v8::Object;
+using v8::String;
 using v8::Value;
 
 // The config binding is used to provide an internal view of compile time
@@ -85,6 +86,21 @@ static void Initialize(Local<Object> target,
   READONLY_TRUE_PROPERTY(target, "hasDtrace");
 #endif
 
+#if defined NODE_DEFAULT_PACKAGE_TYPE
+  READONLY_PROPERTY(target,
+                    "defaultPackageType",
+                    String::NewFromOneByte(isolate,
+                      reinterpret_cast<const unsigned char *>(
+                        NODE_DEFAULT_PACKAGE_TYPE))
+                      .ToLocalChecked());
+#else
+  READONLY_PROPERTY(target,
+                    "defaultPackageType",
+                    String::NewFromOneByte(isolate,
+                      reinterpret_cast<const unsigned char *>("commonjs"))
+                    .ToLocalChecked());
+#endif
+
   READONLY_PROPERTY(target, "hasCachedBuiltins",
      v8::Boolean::New(isolate, native_module::has_code_cache));
 }  // InitConfig