Irp implementation

doc/api/cli.md

@@ -83,13 +83,6 @@ added: v6.0.0
 Enable FIPS-compliant crypto at startup. (Requires Node.js to be built with
 `./configure --openssl-fips`.)
 
-### `--experimental-modules`
-<!-- YAML
-added: v8.5.0
--->
-
-Enable experimental ES module support and caching modules.
-
 ### `--experimental-repl-await`
 <!-- YAML
 added: v10.0.0

doc/api/errors.md

@@ -1788,14 +1788,6 @@ A Unix group or user identifier that does not exist was passed.
 
 An invalid or unknown encoding option was passed to an API.
 
-<a id="ERR_UNKNOWN_FILE_EXTENSION"></a>
-### ERR_UNKNOWN_FILE_EXTENSION
-
-> Stability: 1 - Experimental
-
-An attempt was made to load a module with an unknown or unsupported file
-extension.
-
 <a id="ERR_UNKNOWN_MODULE_FORMAT"></a>
 ### ERR_UNKNOWN_MODULE_FORMAT
 
@@ -1809,6 +1801,14 @@ An attempt was made to load a module with an unknown or unsupported format.
 An invalid or unknown process signal was passed to an API expecting a valid
 signal (such as [`subprocess.kill()`][]).
 
+<a id="ERR_UNSUPPORTED_FILE_EXTENSION"></a>
+### ERR_UNSUPPORTED_FILE_EXTENSION
+
+> Stability: 1 - Experimental
+
+An attempt was made to load a module with an unknown or unsupported file
+extension.
+
 <a id="ERR_V8BREAKITERATOR"></a>
 ### ERR_V8BREAKITERATOR
 

doc/api/esm.md

@@ -18,14 +18,10 @@ interoperability support, specifier resolution, and default behavior.
 
 <!-- type=misc -->
 
-The `--experimental-modules` flag can be used to enable features for loading
-ESM modules.
-
-Once this has been set, files ending with `.mjs` will be able to be loaded
-as ES Modules.
+Modules are enabled by default for files ending with `.mjs`:
 
 ```sh
-node --experimental-modules my-app.mjs
+node my-app.mjs
 ```
 
 ## Features
@@ -55,10 +51,6 @@ property:
 
 ## Notable differences between `import` and `require`
 
-### Only Support for .mjs
-
-ESM must have the `.mjs` extension.
-
 ### Mandatory file extensions
 
 You must provide a file extension when using the `import` keyword.
@@ -157,37 +149,179 @@ The resolver has the following properties:
 
 ### Resolver Algorithm
 
-The algorithm to resolve an ES module specifier is provided through
-_ESM_RESOLVE_:
+The algorithm to load an ES module specifier is given through the
+**ESM_RESOLVE** method below. It returns the resolved URL for a
+module specifier relative to a parentURL, in addition to the unique module
+format for that resolved URL given by the **ESM_FORMAT** routine.
+
+The _"esm"_ format is returned for an ECMAScript Module, while the
+_"legacy"_ format is used to indicate loading through the legacy
+CommonJS loader. Additional formats such as _"wasm"_ or _"addon"_ can be
+extended in future updates.
 
-**ESM_RESOLVE**(_specifier_, _parentURL_)
-> 1. Let _resolvedURL_ be _undefined_.
-> 1. If _specifier_ is a valid URL then,
+In the following algorithms, all subroutine errors are propogated as errors
+of these top-level routines.
+
+_isMain_ is **true** when resolving the Node.js application entry point.
+
+**ESM_RESOLVE(_specifier_, _parentURL_, _isMain_)**
+> 1. Let _resolvedURL_ be **undefined**.
+> 1. If _specifier_ is a valid URL, then
 >    1. Set _resolvedURL_ to the result of parsing and reserializing
 >       _specifier_ as a URL.
-> 1. Otherwise, if _specifier_ starts with _"/"_, _"./"_ or _"../"_ then,
+> 1. Otherwise, if _specifier_ starts with _"/"_, then
+>    1. Throw an _Invalid Specifier_ error.
+> 1. Otherwise, if _specifier_ starts with _"./"_ or _"../"_, then
 >    1. Set _resolvedURL_ to the URL resolution of _specifier_ relative to
 >       _parentURL_.
 > 1. Otherwise,
 >    1. Note: _specifier_ is now a bare specifier.
 >    1. Set _resolvedURL_ the result of
 >       **PACKAGE_RESOLVE**(_specifier_, _parentURL_).
-> 1. If the file at _resolvedURL_ does not exist then,
+> 1. If the file at _resolvedURL_ does not exist, then
 >    1. Throw a _Module Not Found_ error.
-> 1. Return _resolvedURL_.
-
-**PACKAGE_RESOLVE**(_packageSpecifier_, _parentURL_)
-> 1. Assert: _packageSpecifier_ is a bare specifier.
-> 1. If _packageSpecifier_ is a Node.js builtin module then,
+> 1. Let _format_ be the result of **ESM_FORMAT**(_url_, _isMain_).
+> 1. Load _resolvedURL_ as module format, _format_.
+
+PACKAGE_RESOLVE(_packageSpecifier_, _parentURL_)
+> 1. Let _packageName_ be *undefined*.
+> 1. Let _packageSubpath_ be *undefined*.
+> 1. If _packageSpecifier_ is an empty string, then
+>    1. Throw an _Invalid Specifier_ error.
+> 1. If _packageSpecifier_ does not start with _"@"_, then
+>    1. Set _packageName_ to the substring of _packageSpecifier_ until the
+>       first _"/"_ separator or the end of the string.
+> 1. Otherwise,
+>    1. If _packageSpecifier_ does not contain a _"/"_ separator, then
+>       1. Throw an _Invalid Specifier_ error.
+>    1. Set _packageName_ to the substring of _packageSpecifier_
+>       until the second _"/"_ separator or the end of the string.
+> 1. Let _packageSubpath_ be the substring of _packageSpecifier_ from the
+>    position at the length of _packageName_ plus one, if any.
+> 1. Assert: _packageName_ is a valid package name or scoped package name.
+> 1. Assert: _packageSubpath_ is either empty, or a path without a leading
+>    separator.
+> 1. If _packageSubpath_ contains any _"."_ or _".."_ segments or percent
+>    encoded strings for _"/"_ or _"\"_ then,
+>    1. Throw an _Invalid Specifier_ error.
+> 1. If _packageSubpath_ is empty and _packageName_ is a Node.js builtin
+>    module, then
 >    1. Return the string _"node:"_ concatenated with _packageSpecifier_.
-> 1. While _parentURL_ contains a non-empty _pathname_,
+> 1. While _parentURL_ is not the file system root,
 >    1. Set _parentURL_ to the parent folder URL of _parentURL_.
 >    1. Let _packageURL_ be the URL resolution of the string concatenation of
->       _parentURL_, _"/node_modules/"_ and _"packageSpecifier"_.
->    1. If the file at _packageURL_ exists then,
->       1. Return _packageURL_.
+>       _parentURL_, _"/node_modules/"_ and _packageSpecifier_.
+>    1. If the folder at _packageURL_ does not exist, then
+>       1. Set _parentURL_ to the parent URL path of _parentURL_.
+>       1. Continue the next loop iteration.
+>    1. Let _pjson_be the result of **READ_PACKAGE_JSON**(_packageURL_).
+>    1. If _packageSubpath_ is empty, then
+>       1. Return the result of **PACKAGE_MAIN_RESOLVE**(_packageURL_,
+>          _pjson_).
+>    1. Otherwise,
+>       1. If **HAS_ESM_PROPERTIES**(_pjson_) is *true*, then
+>          1. Return **PACKAGE_EXPORTS_RESOLVE**(_packageURL_, _packagePath_,
+>             _pjson_).
+>       1. Return the URL resolution of _packagePath_ in _packageURL_.
+> 1. Throw a _Module Not Found_ error.
+
+PACKAGE_MAIN_RESOLVE(_packageURL_, _pjson_)
+> 1. Let _pjsonURL_ be the URL of the file _"package.json"_ within the parent
+>    path _packageURL_.
+> 1. If **HAS_ESM_PROPERTIES**(_pjson_) is **false**, then
+>    1. Let _mainURL_ be the result applying the legacy
+>       **LOAD_AS_DIRECTORY** CommonJS resolver to _packageURL_, throwing a
+>       _Module Not Found_ error for no resolution.
+>    1. Return _mainURL_.
+> 1. If _pjson.exports_ is a String, then
+>    1. Return the URL of _pjson.exports_ within the parent path _packageURL_.
+> 1. Assert: _pjson.exports_ is an Object.
+> 1. If _pjson.exports["."]_ is a String, then
+>    1. Let _target_ be _pjson.exports["."]_.
+>    1. If **IS_VALID_EXPORTS_TARGET**(_target_) is **false**, then
+>       1. Emit an _"Invalid Exports Target"_ warning.
+>    1. Otherwise,
+>       1. Return the URL of _pjson.exports.default_ within the parent path
+>          _packageURL_.
+> 1. Return **null**.
+
+PACKAGE_EXPORTS_RESOLVE(_packageURL_, _packagePath_, _pjson_)
+> 1. Assert: _pjson_ is not **null**.
+> 1. If _pjson.exports_ is a String, then
+>    1. Throw a _Module Not Found_ error.
+> 1. Assert: _pjson.exports_ is an Object.
+> 1. Set _packagePath_ to _"./"_ concatenated with _packagePath_.
+> 1. If _packagePath_ is a key of _pjson.exports_, then
+>    1. Let _target_ be the value of _pjson.exports[packagePath]_.
+>    1. If **IS_VALID_EXPORTS_TARGET**(_target_) is **false**, then
+>       1. Emit an _"Invalid Exports Target"_ warning.
+>       1. Throw a _Module Not Found_ error.
+>    1. Return the URL resolution of the concatenation of _packageURL_ and
+>       _target_.
+> 1. Let _directoryKeys_ be the list of keys of _pjson.exports_ ending in
+>    _"/"_, sorted by length descending.
+> 1. For each key _directory_ in _directoryKeys_, do
+>    1. If _packagePath_ starts with _directory_, then
+>       1. Let _target_ be the value of _pjson.exports[directory]_.
+>       1. If **IS_VALID_EXPORTS_TARGET**(_target_) is **false** or _target_
+>          does not end in _"/"_, then
+>          1. Emit an _"Invalid Exports Target"_ warning.
+>          1. Continue the loop.
+>       1. Let _subpath_ be the substring of _target_ starting at the index of
+>          the length of _directory_.
+>       1. Return the URL resolution of the concatenation of _packageURL_,
+>          _target_ and _subpath_.
 > 1. Throw a _Module Not Found_ error.
 
+IS_VALID_EXPORTS_TARGET(_target_)
+> 1. If _target_ is not a valid String, then
+>    1. Return **false**.
+> 1. If _target_ does not start with _"./"_, then
+>    1. Return **false**.
+> 1. If _target_ contains any _".."_ or _"."_ path segments, then
+>    1. Return **false**.
+> 1. If _target_ contains any percent-encoded characters for _"/"_ or _"\"_,
+>    then
+>    1. Return **false**.
+> 1. Return **true**.
+
+**ESM_FORMAT(_url_, _isMain_)**
+> 1. Assert: _url_ corresponds to an existing file.
+> 1. Let _pjson_ be the result of **READ_PACKAGE_BOUNDARY**(_url_).
+> 1. If _pjson_ is **null** and _isMain_ is **true**, then
+>    1. Return _"legacy"_.
+> 1. If **HAS_ESM_PROPERTIES**(_pjson_) is **true**, then
+>    1. If _url_ does not end in _".js"_ or _".mjs"_, then
+>       1. Throw an _Unsupported File Extension_ error.
+>    1. Return _"esm"_.
+> 1. Otherwise,
+>    1. If _url_ ends in _".mjs"_, then
+>       1. Return _"esm"_.
+>    1. Otherwise,
+>       1. Return _"legacy"_.
+
+READ_PACKAGE_BOUNDARY(_url_)
+> 1. Let _boundaryURL_ be _url_.
+> 1. While _boundaryURL_ is not the file system root,
+>    1. Let _pjson_ be the result of **READ_PACKAGE_JSON**(_boundaryURL_).
+>    1. If _pjson_ is not **null**, then
+>       1. Return _pjson_.
+>    1. Set _boundaryURL_ to the parent URL of _boundaryURL_.
+> 1. Return **null**.
+
+READ_PACKAGE_JSON(_packageURL_)
+> 1. Let _pjsonURL_ be the resolution of _"package.json"_ within _packageURL_.
+> 1. If the file at _pjsonURL_ does not exist, then
+>    1. Return **null**.
+> 1. If the file at _packageURL_ does not parse as valid JSON, then
+>    1. Throw an _Invalid Package Configuration_ error.
+> 1. Return the parsed JSON source of the file at _url_.
+
+HAS_ESM_PROPERTIES(_pjson_)
+> 1. If _pjson_ is not **null** and _pjson.exports_ is a String or Object, then
+>    1. Return *true*.
+> 1. Return *false*.
+
 [Node.js EP for ES Modules]: https://github.com/nodejs/node-eps/blob/master/002-es-modules.md
 [`module.createRequireFromPath()`]: modules.html#modules_module_createrequirefrompath_filename
 [ESM Minimal Kernel]: https://github.com/nodejs/modules/blob/master/doc/plan-for-new-modules-implementation.md

lib/internal/bootstrap/loaders.js

@@ -316,7 +316,7 @@ NativeModule.prototype.compile = function() {
     const fn = compileFunction(id);
     fn(this.exports, requireFn, this, process, internalBinding);
 
-    if (config.experimentalModules && this.canBeRequiredByUsers) {
+    if (this.canBeRequiredByUsers) {
       this.proxifyExports();
     }
 

lib/internal/bootstrap/node.js

@@ -217,15 +217,7 @@ function startup() {
       'DeprecationWarning', 'DEP0062', startup, true);
   }
 
-  const experimentalModules = getOptionValue('--experimental-modules');
-  if (experimentalModules) {
-    if (experimentalModules) {
-      process.emitWarning(
-        'The ESM module loader is experimental.',
-        'ExperimentalWarning', undefined);
-    }
-    NativeModule.require('internal/process/esm_loader').setup();
-  }
+  NativeModule.require('internal/process/esm_loader').setup();
 
   const { deprecate } = NativeModule.require('internal/util');
   {
@@ -425,11 +417,20 @@ function executeUserCode() {
       process.exit(0);
     }
 
-    // Note: this actually tries to run the module as a ESM first if
-    // --experimental-modules is on.
-    // TODO(joyeecheung): can we move that logic to here? Note that this
-    // is an undocumented method available via `require('module').runMain`
-    CJSModule.runMain();
+    // Load the main module--the command line argument.
+    const { pathToFileURL } = NativeModule.require('url');
+    const asyncESM = NativeModule.require('internal/process/esm_loader');
+    const decorateErrorStack =
+        NativeModule.require('internal/util').decorateErrorStack;
+    asyncESM.loaderPromise.then((loader) =>
+      loader.import(pathToFileURL(process.argv[1]).pathname)
+    )
+    .catch((e) => {
+      decorateErrorStack(e);
+      console.error(e);
+      process.exit(1);
+    });
+    process._tickCallback();
     return;
   }
 

lib/internal/errors.js

@@ -842,13 +842,6 @@ E('ERR_MISSING_ARGS',
 E('ERR_MISSING_DYNAMIC_INSTANTIATE_HOOK',
   'The ES Module loader may not return a format of \'dynamic\' when no ' +
   'dynamicInstantiate function was provided', Error);
-E('ERR_MODULE_NOT_FOUND', (module, base, legacyResolution) => {
-  let msg = `Cannot find module '${module}' imported from ${base}.`;
-  if (legacyResolution)
-    msg += ' Legacy behavior in require() would have found it at ' +
-           legacyResolution;
-  return msg;
-}, Error);
 E('ERR_MULTIPLE_CALLBACK', 'Callback called multiple times', Error);
 E('ERR_NAPI_CONS_FUNCTION', 'Constructor must be a function', TypeError);
 E('ERR_NAPI_INVALID_DATAVIEW_ARGS',
@@ -947,10 +940,10 @@ E('ERR_UNKNOWN_CREDENTIAL', '%s identifier does not exist: %s', Error);
 E('ERR_UNKNOWN_ENCODING', 'Unknown encoding: %s', TypeError);
 
 // This should probably be a `TypeError`.
-E('ERR_UNKNOWN_FILE_EXTENSION', 'Unknown file extension: \'%s\' imported ' +
-  'from %s', Error);
 E('ERR_UNKNOWN_MODULE_FORMAT', 'Unknown module format: %s', RangeError);
 E('ERR_UNKNOWN_SIGNAL', 'Unknown signal: %s', TypeError);
+E('ERR_UNSUPPORTED_FILE_EXTENSION', 'Unsupported file extension: \'%s\' ' +
+  'imported from %s', Error);
 
 E('ERR_V8BREAKITERATOR',
   'Full ICU data not installed. See https://github.com/nodejs/node/wiki/Intl',