esm: emit experimental warnings in common place

PR-URL: https://github.com/nodejs/node/pull/42314
Reviewed-By: Antoine du Hamel <duhamelantoine1995@gmail.com>
Reviewed-By: Geoffrey Booth <webadmin@geoffreybooth.com>

3 files changed, 24 insertions, 11 deletions

diff --git a/lib/internal/modules/esm/loader.js b/lib/internal/modules/esm/loader.js
index 16b832527f7..0dccfebbd4f 100644
--- a/lib/internal/modules/esm/loader.js
+++ b/lib/internal/modules/esm/loader.js
@@ -31,6 +31,7 @@ const {
   ERR_UNKNOWN_MODULE_FORMAT
 } = require('internal/errors').codes;
 const { pathToFileURL, isURLInstance, URL } = require('internal/url');
+const { emitExperimentalWarning } = require('internal/util');
 const {
   isAnyArrayBuffer,
   isArrayBufferView,
@@ -53,6 +54,13 @@ const {
   fetchModule,
 } = require('internal/modules/esm/fetch_module');
 
+
+/**
+ * Prevent the specifier resolution warning from being printed twice
+ */
+let emittedSpecifierResolutionWarning = false;
+
+
 /**
  * An ESMLoader instance is used as the main entry point for loading ES modules.
  * Currently, this is a singleton -- there is only one used for loading
@@ -107,6 +115,22 @@ class ESMLoader {
    */
   translators = translators;
 
+  constructor() {
+    if (getOptionValue('--experimental-loader')) {
+      emitExperimentalWarning('Custom ESM Loaders');
+    }
+    if (getOptionValue('--experimental-network-imports')) {
+      emitExperimentalWarning('Network Imports');
+    }
+    if (getOptionValue('--experimental-specifier-resolution') === 'node' && !emittedSpecifierResolutionWarning) {
+      process.emitWarning(
+        'The Node.js specifier resolution flag is experimental. It could change or be removed at any time.',
+        'ExperimentalWarning'
+      );
+      emittedSpecifierResolutionWarning = true;
+    }
+  }
+
   static pluckHooks({
     globalPreload,
     resolve,
diff --git a/lib/internal/modules/esm/resolve.js b/lib/internal/modules/esm/resolve.js
index 53085f32746..e640947450c 100644
--- a/lib/internal/modules/esm/resolve.js
+++ b/lib/internal/modules/esm/resolve.js
@@ -364,7 +364,6 @@ function resolveDirectoryEntry(search) {
 }
 
 const encodedSepRegEx = /%2F|%5C/i;
-let experimentalSpecifierResolutionWarned = false;
 /**
  * @param {URL} resolved
  * @param {string | URL | undefined} base
@@ -379,13 +378,6 @@ function finalizeResolution(resolved, base, preserveSymlinks) {
 
   let path = fileURLToPath(resolved);
   if (getOptionValue('--experimental-specifier-resolution') === 'node') {
-    if (!experimentalSpecifierResolutionWarned) {
-      process.emitWarning(
-        'The Node.js specifier resolution flag is experimental. It could change or be removed at any time.',
-        'ExperimentalWarning');
-      experimentalSpecifierResolutionWarned = true;
-    }
-
     let file = resolveExtensionsWithTryExactName(resolved);
 
     // Directory
diff --git a/lib/internal/process/esm_loader.js b/lib/internal/process/esm_loader.js
index 73385a85b4e..20021134ce4 100644
--- a/lib/internal/process/esm_loader.js
+++ b/lib/internal/process/esm_loader.js
@@ -55,9 +55,6 @@ async function initializeLoader() {
 
   if (!customLoaders.length) return;
 
-  const { emitExperimentalWarning } = require('internal/util');
-  emitExperimentalWarning('--experimental-loader');
-
   let cwd;
   try {
     cwd = process.cwd() + '/';