module: remove --experimental-default-type

PR-URL: #56092
Reviewed-By: Yagiz Nizipli <yagiz@nizipli.com>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Jacob Smith <jacob@frende.me>

Author: GeoffreyBooth

doc/api/cli.md

@@ -25,16 +25,14 @@ For more info about `node inspect`, see the [debugger][] documentation.
 
 The program entry point is a specifier-like string. If the string is not an
 absolute path, it's resolved as a relative path from the current working
-directory. That path is then resolved by [CommonJS][] module loader, or by the
-[ES module loader][Modules loaders] if [`--experimental-default-type=module`][]
-is passed. If no corresponding file is found, an error is thrown.
+directory. That path is then resolved by [CommonJS][] module loader. If no
+corresponding file is found, an error is thrown.
 
 If a file is found, its path will be passed to the
 [ES module loader][Modules loaders] under any of the following conditions:
 
 * The program was started with a command-line flag that forces the entry
-  point to be loaded with ECMAScript module loader, such as `--import` or
-  [`--experimental-default-type=module`][].
+  point to be loaded with ECMAScript module loader, such as `--import`.
 * The file has an `.mjs` extension.
 * The file does not have a `.cjs` extension, and the nearest parent
   `package.json` file contains a top-level [`"type"`][] field with a value of
@@ -47,9 +45,8 @@ Otherwise, the file is loaded using the CommonJS module loader. See
 
 When loading, the [ES module loader][Modules loaders] loads the program
 entry point, the `node` command will accept as input only files with `.js`,
-`.mjs`, or `.cjs` extensions; with `.wasm` extensions when
-[`--experimental-wasm-modules`][] is enabled; and with no extension when
-[`--experimental-default-type=module`][] is passed.
+`.mjs`, or `.cjs` extensions; and with `.wasm` extensions when
+[`--experimental-wasm-modules`][] is enabled.
 
 ## Options
 
@@ -896,38 +893,6 @@ and `"` are usable.
 It is possible to run code containing inline types by passing
 [`--experimental-strip-types`][].
 
-### `--experimental-default-type=type`
-
-<!-- YAML
-added:
-  - v21.0.0
-  - v20.10.0
-  - v18.19.0
--->
-
-> Stability: 1.0 - Early development
-
-Define which module system, `module` or `commonjs`, to use for the following:
-
-* String input provided via `--eval` or STDIN, if `--input-type` is unspecified.
-
-* Files ending in `.js` or with no extension, if there is no `package.json` file
-  present in the same folder or any parent folder.
-
-* Files ending in `.js` or with no extension, if the nearest parent
-  `package.json` field lacks a `"type"` field; unless the `package.json` folder
-  or any parent folder is inside a `node_modules` folder.
-
-In other words, `--experimental-default-type=module` flips all the places where
-Node.js currently defaults to CommonJS to instead default to ECMAScript modules,
-with the exception of folders and subfolders below `node_modules`, for backward
-compatibility.
-
-Under `--experimental-default-type=module` and `--experimental-wasm-modules`,
-files with no extension will be treated as WebAssembly if they begin with the
-WebAssembly magic number (`\0asm`); otherwise they will be treated as ES module
-JavaScript.
-
 ### `--experimental-transform-types`
 
 <!-- YAML
@@ -1404,7 +1369,7 @@ added: v12.0.0
 
 This configures Node.js to interpret `--eval` or `STDIN` input as CommonJS or
 as an ES module. Valid values are `"commonjs"` or `"module"`. The default is
-`"commonjs"` unless [`--experimental-default-type=module`][] is used.
+`"commonjs"`.
 
 The REPL does not support this option. Usage of `--input-type=module` with
 [`--print`][] will throw an error, as `--print` does not support ES module
@@ -3057,7 +3022,6 @@ one is included in the list below.
 * `--enable-source-maps`
 * `--entry-url`
 * `--experimental-abortcontroller`
-* `--experimental-default-type`
 * `--experimental-detect-module`
 * `--experimental-eventsource`
 * `--experimental-import-meta-resolve`
@@ -3620,7 +3584,6 @@ node --stack-trace-limit=12 -p -e "Error.stackTraceLimit" # prints 12
 [`--diagnostic-dir`]: #--diagnostic-dirdirectory
 [`--env-file-if-exists`]: #--env-file-if-existsconfig
 [`--env-file`]: #--env-fileconfig
-[`--experimental-default-type=module`]: #--experimental-default-typetype
 [`--experimental-sea-config`]: single-executable-applications.md#generating-single-executable-preparation-blobs
 [`--experimental-strip-types`]: #--experimental-strip-types
 [`--experimental-wasm-modules`]: #--experimental-wasm-modules

doc/api/esm.md

@@ -124,14 +124,13 @@ Node.js has two module systems: [CommonJS][] modules and ECMAScript modules.
 
 Authors can tell Node.js to interpret JavaScript as an ES module via the `.mjs`
 file extension, the `package.json` [`"type"`][] field with a value `"module"`,
-the [`--input-type`][] flag with a value of `"module"`, or the
-[`--experimental-default-type`][] flag with a value of `"module"`. These are
-explicit markers of code being intended to run as an ES module.
+or the [`--input-type`][] flag with a value of `"module"`. These are explicit
+markers of code being intended to run as an ES module.
 
-Inversely, authors can tell Node.js to interpret JavaScript as CommonJS via the
-`.cjs` file extension, the `package.json` [`"type"`][] field with a value
-`"commonjs"`, the [`--input-type`][] flag with a value of `"commonjs"`, or the
-[`--experimental-default-type`][] flag with a value of `"commonjs"`.
+Inversely, authors can explicitly tell Node.js to interpret JavaScript as
+CommonJS via the `.cjs` file extension, the `package.json` [`"type"`][] field
+with a value `"commonjs"`, or the [`--input-type`][] flag with a value of
+`"commonjs"`.
 
 When code lacks explicit markers for either module system, Node.js will inspect
 the source code of a module to look for ES module syntax. If such syntax is
@@ -1124,7 +1123,6 @@ resolution for ESM specifiers is [commonjs-extension-resolution-loader][].
 [URL]: https://url.spec.whatwg.org/
 [`"exports"`]: packages.md#exports
 [`"type"`]: packages.md#type
-[`--experimental-default-type`]: cli.md#--experimental-default-typetype
 [`--input-type`]: cli.md#--input-typetype
 [`data:` URLs]: https://developer.mozilla.org/en-US/docs/Web/HTTP/Basics_of_HTTP/Data_URIs
 [`export`]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/export

doc/api/module.md

@@ -980,8 +980,7 @@ Omitting vs providing a `source` for `'commonjs'` has very different effects:
   registered hooks. This behavior for nullish `source` is temporary — in the
   future, nullish `source` will not be supported.
 
-When `node` is run with `--experimental-default-type=commonjs`, the Node.js
-internal `load` implementation, which is the value of `next` for the
+The Node.js internal `load` implementation, which is the value of `next` for the
 last hook in the `load` chain, returns `null` for `source` when `format` is
 `'commonjs'` for backward compatibility. Here is an example hook that would
 opt-in to using the non-default behavior:

doc/api/packages.md

@@ -73,10 +73,9 @@ expressions:
   `import` or `export` statements or `import.meta`, with no explicit marker of
   how it should be interpreted. Explicit markers are `.mjs` or `.cjs`
   extensions, `package.json` `"type"` fields with either `"module"` or
-  `"commonjs"` values, or `--input-type` or `--experimental-default-type` flags.
-  Dynamic `import()` expressions are supported in either CommonJS or ES modules
-  and would not force a file to be treated as an ES module. See
-  [Syntax detection][].
+  `"commonjs"` values, or the `--input-type` flag. Dynamic `import()`
+  expressions are supported in either CommonJS or ES modules and would not force
+  a file to be treated as an ES module. See [Syntax detection][].
 
 Node.js will treat the following as [CommonJS][] when passed to `node` as the
 initial input, or when referenced by `import` statements or `import()`
@@ -90,30 +89,21 @@ expressions:
 * Strings passed in as an argument to `--eval` or `--print`, or piped to `node`
   via `STDIN`, with the flag `--input-type=commonjs`.
 
-Aside from these explicit cases, there are other cases where Node.js defaults to
-one module system or the other based on the value of the
-[`--experimental-default-type`][] flag:
-
-* Files ending in `.js` or with no extension, if there is no `package.json` file
-  present in the same folder or any parent folder.
-
-* Files ending in `.js` or with no extension, if the nearest parent
-  `package.json` field lacks a `"type"` field; unless the folder is inside a
-  `node_modules` folder. (Package scopes under `node_modules` are always treated
-  as CommonJS when the `package.json` file lacks a `"type"` field, regardless
-  of `--experimental-default-type`, for backward compatibility.)
-
-* Strings passed in as an argument to `--eval` or piped to `node` via `STDIN`,
-  when `--input-type` is unspecified.
-
-This flag currently defaults to `"commonjs"`, but it may change in the future to
-default to `"module"`. For this reason it is best to be explicit wherever
-possible; in particular, package authors should always include the [`"type"`][]
-field in their `package.json` files, even in packages where all sources are
-CommonJS. Being explicit about the `type` of the package will future-proof the
-package in case the default type of Node.js ever changes, and it will also make
-things easier for build tools and loaders to determine how the files in the
-package should be interpreted.
+* Files with a `.js` extension with no parent `package.json` file or where the
+  nearest parent `package.json` file lacks a `type` field, and where the code
+  can evaluate successfully as CommonJS. In other words, Node.js tries to run
+  such "ambiguous" files as CommonJS first, and will retry evaluating them as ES
+  modules if the evaluation as CommonJS fails because the parser found ES module
+  syntax.
+
+Writing ES module syntax in "ambiguous" files incurs a performance cost, and
+therefore it is encouraged that authors be explicit wherever possible. In
+particular, package authors should always include the [`"type"`][] field in
+their `package.json` files, even in packages where all sources are CommonJS.
+Being explicit about the `type` of the package will future-proof the package in
+case the default type of Node.js ever changes, and it will also make things
+easier for build tools and loaders to determine how the files in the package
+should be interpreted.
 
 ### Syntax detection
 
@@ -137,10 +127,8 @@ as an ES module.
 Ambiguous input is defined as:
 
 * Files with a `.js` extension or no extension; and either no controlling
-  `package.json` file or one that lacks a `type` field; and
-  `--experimental-default-type` is not specified.
-* String input (`--eval` or STDIN) when neither `--input-type` nor
-  `--experimental-default-type` are specified.
+  `package.json` file or one that lacks a `type` field.
+* String input (`--eval` or `STDIN`) when `--input-type`is not specified.
 
 ES module syntax is defined as syntax that would throw when evaluated as
 CommonJS. This includes the following:
@@ -1162,7 +1150,6 @@ This field defines [subpath imports][] for the current package.
 [`"packageManager"`]: #packagemanager
 [`"type"`]: #type
 [`--conditions` / `-C` flag]: #resolving-user-conditions
-[`--experimental-default-type`]: cli.md#--experimental-default-typetype
 [`--no-addons` flag]: cli.md#--no-addons
 [`ERR_PACKAGE_PATH_NOT_EXPORTED`]: errors.md#err_package_path_not_exported
 [`package.json`]: #nodejs-packagejson-field-definitions

doc/node.1

@@ -163,11 +163,6 @@ Enable Source Map V3 support for stack traces.
 .It Fl -entry-url
 Interpret the entry point as a URL.
 .
-.It Fl -experimental-default-type Ns = Ns Ar type
-Interpret as either ES modules or CommonJS modules input via --eval or STDIN, when --input-type is unspecified;
-.js or extensionless files with no sibling or parent package.json;
-.js or extensionless files whose nearest parent package.json lacks a "type" field, unless under node_modules.
-.
 .It Fl -experimental-import-meta-resolve
 Enable experimental ES modules support for import.meta.resolve().
 .

lib/internal/main/check_syntax.js

@@ -59,9 +59,7 @@ function loadESMIfNeeded(cb) {
 async function checkSyntax(source, filename) {
   let format;
   if (filename === '[stdin]' || filename === '[eval]') {
-    format = (getOptionValue('--input-type') === 'module' ||
-      (getOptionValue('--experimental-default-type') === 'module' && getOptionValue('--input-type') !== 'commonjs')) ?
-      'module' : 'commonjs';
+    format = (getOptionValue('--input-type') === 'module') ? 'module' : 'commonjs';
   } else {
     const { defaultResolve } = require('internal/modules/esm/resolve');
     const { defaultGetFormat } = require('internal/modules/esm/get_format');

lib/internal/main/eval_stdin.js

@@ -25,8 +25,7 @@ readStdin((code) => {
 
   const print = getOptionValue('--print');
   const shouldLoadESM = getOptionValue('--import').length > 0;
-  if (getOptionValue('--input-type') === 'module' ||
-    (getOptionValue('--experimental-default-type') === 'module' && getOptionValue('--input-type') !== 'commonjs')) {
+  if (getOptionValue('--input-type') === 'module') {
     evalModuleEntryPoint(code, print);
   } else {
     evalScript('[stdin]',

lib/internal/main/eval_string.js

@@ -29,8 +29,7 @@ const source = getOptionValue('--experimental-strip-types') ?
 
 const print = getOptionValue('--print');
 const shouldLoadESM = getOptionValue('--import').length > 0 || getOptionValue('--experimental-loader').length > 0;
-if (getOptionValue('--input-type') === 'module' ||
-  (getOptionValue('--experimental-default-type') === 'module' && getOptionValue('--input-type') !== 'commonjs')) {
+if (getOptionValue('--input-type') === 'module') {
   evalModuleEntryPoint(source, print);
 } else {
   // For backward compatibility, we want the identifier crypto to be the

lib/internal/main/run_main_module.js

@@ -23,15 +23,11 @@ if (isEntryURL) {
   emitExperimentalWarning('--entry-url');
 }
 
-if (getOptionValue('--experimental-default-type') === 'module') {
-  require('internal/modules/run_main').executeUserEntryPoint(mainEntry);
-} else {
-  /**
-   * To support legacy monkey-patching of `Module.runMain`, we call `runMain` here to have the CommonJS loader begin
-   * the execution of the main entry point, even if the ESM loader immediately takes over because the main entry is an
-   * ES module or one of the other opt-in conditions (such as the use of `--import`) are met. Users can monkey-patch
-   * before the main entry point is loaded by doing so via scripts loaded through `--require`. This monkey-patchability
-   * is undesirable and is removed in `--experimental-default-type=module` mode.
-   */
-  require('internal/modules/cjs/loader').Module.runMain(mainEntry);
-}
+/**
+ * To support legacy monkey-patching of `Module.runMain`, we call `runMain` here to have the CommonJS loader begin the
+ * execution of the main entry point, even if the ESM loader immediately takes over because the main entry is an ES
+ * module or one of the other opt-in conditions (such as the use of `--import`) are met. Users can monkey-patch before
+ * the main entry point is loaded by doing so via scripts loaded through `--require`. This monkey-patchability is
+ * undesirable and should be removed once the module customization hooks provide equivalent functionality.
+ */
+require('internal/modules/cjs/loader').Module.runMain(mainEntry);

lib/internal/modules/esm/formats.js

@@ -46,8 +46,8 @@ function mimeToFormat(mime) {
 }
 
 /**
- * For extensionless files in a `module` package scope, or a default `module` scope enabled by the
- * `--experimental-default-type` flag, we check the file contents to disambiguate between ES module JavaScript and Wasm.
+ * For extensionless files in a `module` package scope, we check the file contents to disambiguate between ES module
+ * JavaScript and Wasm.
  * We do this by taking advantage of the fact that all Wasm files start with the header `0x00 0x61 0x73 0x6d` (`_asm`).
  * @param {URL} url
  */