From c1640e8ff83c2e1f3cd0efa1b1995c9fed337109 Mon Sep 17 00:00:00 2001
From: Efe Karasakal <hi@efe.dev>
Date: Tue, 4 Aug 2026 00:21:08 +0200
Subject: [PATCH 1/2] esm: only register text format when enabled

Signed-off-by: Efe Karasakal <hi@efe.dev>
---
 lib/internal/modules/esm/assert.js            | 18 +++++++++------
 lib/internal/process/pre_execution.js         |  2 ++
 .../es-module/test-esm-loader-text-format.mjs | 23 +++++++++++++++++++
 3 files changed, 36 insertions(+), 7 deletions(-)
 create mode 100644 test/es-module/test-esm-loader-text-format.mjs

diff --git a/lib/internal/modules/esm/assert.js b/lib/internal/modules/esm/assert.js
index 406c0f4e4513..3bb6367b56fb 100644
--- a/lib/internal/modules/esm/assert.js
+++ b/lib/internal/modules/esm/assert.js
@@ -3,6 +3,7 @@
 const {
   ArrayPrototypeFilter,
   ArrayPrototypeIncludes,
+  ArrayPrototypePush,
   ObjectKeys,
   ObjectPrototypeHasOwnProperty,
   ObjectValues,
@@ -30,7 +31,6 @@ const formatTypeMap = {
   'commonjs': kImplicitTypeAttribute,
   'json': 'json',
   'module': kImplicitTypeAttribute,
-  'text': 'text',
   'wasm': kImplicitTypeAttribute, // It's unclear whether the HTML spec will require an type attribute or not for Wasm; see https://github.com/WebAssembly/esm-integration/issues/42
 };
 // NOTE: Don't add bytes support yet as it requires Uint8Arrays backed by immutable ArrayBuffers,
@@ -48,6 +48,15 @@ const supportedTypeAttributes = ArrayPrototypeFilter(
   ObjectValues(formatTypeMap),
   (type) => type !== kImplicitTypeAttribute);
 
+function initializeImportAttributes() {
+  if (getOptionValue('--experimental-import-text') &&
+    formatTypeMap['text'] === undefined
+  ) {
+    formatTypeMap['text'] = 'text';
+    ArrayPrototypePush(supportedTypeAttributes, 'text');
+  }
+}
+
 /**
  * Test a module's import attributes.
  * @param {string} url The URL of the imported module, for error reporting.
@@ -67,12 +76,6 @@ function validateAttributes(url, format,
   }
   const validType = formatTypeMap[format];
 
-  if (validType !== undefined &&
-    importAttributes.type === 'text' &&
-    !getOptionValue('--experimental-import-text')) {
-    throw new ERR_IMPORT_ATTRIBUTE_UNSUPPORTED('type', importAttributes.type, url);
-  }
-
   switch (validType) {
     case undefined:
       // Ignore attributes for module formats we don't recognize, to allow new
@@ -122,6 +125,7 @@ function handleInvalidType(url, type) {
 
 
 module.exports = {
+  initializeImportAttributes,
   kImplicitTypeAttribute,
   validateAttributes,
 };
diff --git a/lib/internal/process/pre_execution.js b/lib/internal/process/pre_execution.js
index 9d5891e7a24a..a07da28fa93b 100644
--- a/lib/internal/process/pre_execution.js
+++ b/lib/internal/process/pre_execution.js
@@ -169,6 +169,8 @@ function prepareExecution(options) {
 
   const { initializeExtensionFormatMap } = require('internal/modules/esm/get_format');
   initializeExtensionFormatMap();
+  const { initializeImportAttributes } = require('internal/modules/esm/assert');
+  initializeImportAttributes();
 
   setupVmModules();
   if (initializeModules) {
diff --git a/test/es-module/test-esm-loader-text-format.mjs b/test/es-module/test-esm-loader-text-format.mjs
new file mode 100644
index 000000000000..2a35992dbcf4
--- /dev/null
+++ b/test/es-module/test-esm-loader-text-format.mjs
@@ -0,0 +1,23 @@
+import '../common/index.mjs';
+import assert from 'node:assert';
+import { registerHooks } from 'node:module';
+
+// A user loader can use `text` with and without import attributes without the feature flag.
+
+registerHooks({
+  load(url, context, nextLoad) {
+    if (url.endsWith('.txt')) {
+      return nextLoad(url, { ...context, format: 'text' });
+    }
+    return nextLoad(url, context);
+  },
+});
+
+const { default: text } = await import('../fixtures/file-to-read-without-bom.txt');
+const { default: empty } = await import(
+  '../fixtures/empty.txt',
+  { with: { type: 'text' } }
+);
+
+assert.strictEqual(text, 'abc\ndef\nghi\n');
+assert.strictEqual(empty, '');

From c26da19a0434370544649a1cfd09ccb54fdfe0e3 Mon Sep 17 00:00:00 2001
From: Efe Karasakal <hi@efe.dev>
Date: Tue, 4 Aug 2026 17:32:21 +0200
Subject: [PATCH 2/2] esm: apply review changes

Signed-off-by: Efe Karasakal <hi@efe.dev>
---
 lib/internal/modules/esm/assert.js | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/lib/internal/modules/esm/assert.js b/lib/internal/modules/esm/assert.js
index 3bb6367b56fb..fcf1368a074c 100644
--- a/lib/internal/modules/esm/assert.js
+++ b/lib/internal/modules/esm/assert.js
@@ -50,9 +50,9 @@ const supportedTypeAttributes = ArrayPrototypeFilter(
 
 function initializeImportAttributes() {
   if (getOptionValue('--experimental-import-text') &&
-    formatTypeMap['text'] === undefined
+    formatTypeMap.text === undefined
   ) {
-    formatTypeMap['text'] = 'text';
+    formatTypeMap.text = 'text';
     ArrayPrototypePush(supportedTypeAttributes, 'text');
   }
 }