module: remove experimental warning from type stripping

PR-URL: #58643 Refs: nodejs/typescript#24 Reviewed-By: Jacob Smith <jacob@frende.me> Reviewed-By: Michaël Zasso <targos@protonmail.com> Reviewed-By: Matteo Collina <matteo.collina@gmail.com> Reviewed-By: Jordan Harband <ljharb@gmail.com> Reviewed-By: James M Snell <jasnell@gmail.com> Reviewed-By: Filip Skokan <panva.ip@gmail.com> Reviewed-By: Ethan Arrowood <ethan@arrowood.dev> Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com> Reviewed-By: Chengzhong Wu <legendecas@gmail.com> Reviewed-By: Chemi Atlow <chemi@atlow.co.il>
nodejs · marco-ippolito · Mar 3, 2025 · May 7, 2025 · Jun 12, 2025 · Jun 11, 2025
commit 59c3c01bc88b007349ee2cada5a7f9e864878b5b
diff --git a/doc/api/typescript.md b/doc/api/typescript.md
@@ -2,6 +2,9 @@
 
 <!-- YAML
 changes:
+  - version: REPLACEME
+    pr-url: https://github.com/nodejs/node/pull/58643
+    description: Type stripping no longer emits an experimental warning.
   - version: REPLACEME
     pr-url: https://github.com/nodejs/node/pull/56350
     description: Type stripping is enabled by default.

diff --git a/lib/internal/modules/typescript.js b/lib/internal/modules/typescript.js
@@ -28,7 +28,8 @@ const { Buffer } = require('buffer');
  * @type {string}
  */
 const getTypeScriptParsingMode = getLazy(() =>
-  (getOptionValue('--experimental-transform-types') ? 'transform' : 'strip-only'),
+  (getOptionValue('--experimental-transform-types') ?
+    (emitExperimentalWarning('Transform Types'), 'transform') : 'strip-only'),
 );
 
 /**
@@ -131,13 +132,9 @@ function processTypeScriptCode(code, options) {
  * It is used by internal loaders.
  * @param {string} source TypeScript code to parse.
  * @param {string} filename The filename of the source code.
- * @param {boolean} emitWarning Whether to emit a warning.
  * @returns {TransformOutput} The stripped TypeScript code.
  */
-function stripTypeScriptModuleTypes(source, filename, emitWarning = true) {
-  if (emitWarning) {
-    emitExperimentalWarning('Type Stripping');
-  }
+function stripTypeScriptModuleTypes(source, filename) {
   assert(typeof source === 'string');
   if (isUnderNodeModules(filename)) {
     throw new ERR_UNSUPPORTED_NODE_MODULES_TYPE_STRIPPING(filename);

diff --git a/lib/internal/process/execution.js b/lib/internal/process/execution.js
@@ -35,7 +35,6 @@ const { getOptionValue } = require('internal/options');
 const {
   makeContextifyScript, runScriptInThisContext,
 } = require('internal/vm');
-const { emitExperimentalWarning } = require('internal/util');
 // shouldAbortOnUncaughtToggle is a typed array for faster
 // communication with JS.
 const { shouldAbortOnUncaughtToggle } = internalBinding('util');
@@ -255,16 +254,14 @@ function evalTypeScript(name, source, breakFirstLine, print, shouldLoadESM = fal
     compiledScript = compileScript(name, source, baseUrl);
   } catch (originalError) {
     try {
-      sourceToRun = stripTypeScriptModuleTypes(source, name, false);
+      sourceToRun = stripTypeScriptModuleTypes(source, kEvalTag);
       // Retry the CJS/ESM syntax detection after stripping the types.
       if (shouldUseModuleEntryPoint(name, sourceToRun)) {
         return evalTypeScriptModuleEntryPoint(source, print);
       }
       // If the ContextifiedScript was successfully created, execute it.
       // outside the try-catch block to avoid catching runtime errors.
       compiledScript = compileScript(name, sourceToRun, baseUrl);
-      // Emit the experimental warning after the code was successfully evaluated.
-      emitExperimentalWarning('Type Stripping');
     } catch (tsError) {
       // If it's invalid or unsupported TypeScript syntax, rethrow the original error
       // with the TypeScript error message added to the stack.
@@ -318,12 +315,10 @@ function evalTypeScriptModuleEntryPoint(source, print) {
         moduleWrap = loader.createModuleWrap(source, url);
       } catch (originalError) {
         try {
-          const strippedSource = stripTypeScriptModuleTypes(source, url, false);
+          const strippedSource = stripTypeScriptModuleTypes(source, kEvalTag);
           // If the moduleWrap was successfully created, execute the module job.
           // outside the try-catch block to avoid catching runtime errors.
           moduleWrap = loader.createModuleWrap(strippedSource, url);
-          // Emit the experimental warning after the code was successfully compiled.
-          emitExperimentalWarning('Type Stripping');
         } catch (tsError) {
           // If it's invalid or unsupported TypeScript syntax, rethrow the original error
           // with the TypeScript error message added to the stack.

diff --git a/test/es-module/test-typescript-eval.mjs b/test/es-module/test-typescript-eval.mjs
@@ -11,7 +11,7 @@ test('eval TypeScript ESM syntax', async () => {
     const text: string = 'Hello, TypeScript!'
     console.log(util.styleText('red', text));`]);
 
-  match(result.stderr, /Type Stripping is an experimental feature and might change at any time/);
+  strictEqual(result.stderr, '');
   match(result.stdout, /Hello, TypeScript!/);
   strictEqual(result.code, 0);
 });
@@ -24,7 +24,7 @@ test('eval TypeScript ESM syntax with input-type module', async () => {
     const text: string = 'Hello, TypeScript!'
     console.log(util.styleText('red', text));`]);
 
-  match(result.stderr, /Type Stripping is an experimental feature and might change at any time/);
+  strictEqual(result.stderr, '');
   match(result.stdout, /Hello, TypeScript!/);
   strictEqual(result.code, 0);
 });
@@ -36,7 +36,7 @@ test('eval TypeScript CommonJS syntax', async () => {
     const text: string = 'Hello, TypeScript!'
     console.log(util.styleText('red', text));`]);
   match(result.stdout, /Hello, TypeScript!/);
-  match(result.stderr, /ExperimentalWarning: Type Stripping is an experimental/);
+  strictEqual(result.stderr, '');
   strictEqual(result.code, 0);
 });
 
@@ -72,7 +72,7 @@ test('TypeScript ESM syntax not specified', async () => {
     `import util from 'node:util'
     const text: string = 'Hello, TypeScript!'
     console.log(text);`]);
-  match(result.stderr, /ExperimentalWarning: Type Stripping is an experimental/);
+  strictEqual(result.stderr, '');
   match(result.stdout, /Hello, TypeScript!/);
   strictEqual(result.code, 0);
 });
@@ -162,7 +162,7 @@ test('check warning is emitted when eval TypeScript CommonJS syntax', async () =
     `const util = require('node:util');
     const text: string = 'Hello, TypeScript!'
     console.log(util.styleText('red', text));`]);
-  match(result.stderr, /ExperimentalWarning: Type Stripping is an experimental/);
+  strictEqual(result.stderr, '');
   match(result.stdout, /Hello, TypeScript!/);
   strictEqual(result.code, 0);
 });

diff --git a/test/es-module/test-typescript-module.mjs b/test/es-module/test-typescript-module.mjs
@@ -20,7 +20,7 @@ test('execute an .mts file importing an .mts file', async () => {
     fixtures.path('typescript/mts/test-import-module.mts'),
   ]);
 
-  match(result.stderr, /Type Stripping is an experimental feature and might change at any time/);
+  strictEqual(result.stderr, '');
   match(result.stdout, /Hello, TypeScript!/);
   strictEqual(result.code, 0);
 });

diff --git a/test/es-module/test-typescript.mjs b/test/es-module/test-typescript.mjs
@@ -35,7 +35,7 @@ test('execute a TypeScript file', async () => {
     fixtures.path('typescript/ts/test-typescript.ts'),
   ]);
 
-  match(result.stderr, /Type Stripping is an experimental feature and might change at any time/);
+  strictEqual(result.stderr, '');
   match(result.stdout, /Hello, TypeScript!/);
   strictEqual(result.code, 0);
 });
@@ -412,3 +412,14 @@ test('execute invalid TypeScript syntax', async () => {
   strictEqual(result.stdout, '');
   strictEqual(result.code, 1);
 });
+
+test('check transform types warning', async () => {
+  const result = await spawnPromisified(process.execPath, [
+    '--experimental-transform-types',
+    fixtures.path('typescript/ts/test-typescript.ts'),
+  ]);
+
+  match(result.stderr, /Transform Types is an experimental feature and might change at any time/);
+  match(result.stdout, /Hello, TypeScript!/);
+  strictEqual(result.code, 0);
+});