esm: make extension-less errors in type:module actionable

PR-URL: #42301
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Jacob Smith <jacob@frende.me>
Reviewed-By: Geoffrey Booth <webadmin@geoffreybooth.com>
Reviewed-By: Antoine du Hamel <duhamelantoine1995@gmail.com>

Author: bmeck

doc/api/esm.md

@@ -1084,7 +1084,7 @@ async function getPackageType(url) {
  // required by the spec
  // this simple truthy check for whether `url` contains a file extension will
  // work for most projects but does not cover some edge-cases (such as
- // extension-less files or a url ending in a trailing space)
+ // extensionless files or a url ending in a trailing space)
  const isFilePath = !!extname(url);
  // If it is a file path, get the directory it's in
  const dir = isFilePath ?

lib/internal/errors.js

@@ -1596,9 +1596,13 @@ E('ERR_UNHANDLED_ERROR',
 E('ERR_UNKNOWN_BUILTIN_MODULE','No such built-in module: %s',Error);
 E('ERR_UNKNOWN_CREDENTIAL','%s identifier does not exist: %s',Error);
 E('ERR_UNKNOWN_ENCODING','Unknown encoding: %s',TypeError);
-E('ERR_UNKNOWN_FILE_EXTENSION',
-'Unknown file extension "%s" for %s',
-TypeError);
+E('ERR_UNKNOWN_FILE_EXTENSION',(ext,path,suggestion)=>{
+letmsg=`Unknown file extension "${ext}" for ${path}`;
+if(suggestion){
+msg+=`. ${suggestion}`;
+}
+returnmsg;
+},TypeError);
 E('ERR_UNKNOWN_MODULE_FORMAT','Unknown module format: %s for URL %s',
 RangeError);
 E('ERR_UNKNOWN_SIGNAL','Unknown signal: %s',TypeError);

lib/internal/modules/esm/get_format.js

@@ -6,8 +6,9 @@ const {
  ObjectPrototypeHasOwnProperty,
  PromisePrototypeThen,
  PromiseResolve,
+ StringPrototypeSlice,
 }=primordials;
-const{ extname }=require('path');
+const{basename,extname, relative}=require('path');
 const{ getOptionValue }=require('internal/options');
 const{ fetchModule }=require('internal/modules/esm/fetch_module');
 const{
@@ -20,7 +21,7 @@ const experimentalNetworkImports =
 getOptionValue('--experimental-network-imports');
 constexperimentalSpecifierResolution=
 getOptionValue('--experimental-specifier-resolution');
-const{ getPackageType }=require('internal/modules/esm/resolve');
+const{ getPackageType, getPackageScopeConfig}=require('internal/modules/esm/resolve');
 const{URL, fileURLToPath }=require('internal/url');
 const{ERR_UNKNOWN_FILE_EXTENSION}=require('internal/errors').codes;
 
@@ -52,7 +53,8 @@ function getDataProtocolModuleFormat(parsed) {
  * @returns {string}
  */
 functiongetFileProtocolModuleFormat(url,context,ignoreErrors){
-constext=extname(url.pathname);
+constfilepath=fileURLToPath(url);
+constext=extname(filepath);
 if(ext==='.js'){
 returngetPackageType(url)==='module' ? 'module' : 'commonjs';
 }
@@ -63,7 +65,19 @@ function getFileProtocolModuleFormat(url, context, ignoreErrors) {
 if(experimentalSpecifierResolution!=='node'){
 // Explicit undefined return indicates load hook should rerun format check
 if(ignoreErrors)returnundefined;
-thrownewERR_UNKNOWN_FILE_EXTENSION(ext,fileURLToPath(url));
+letsuggestion='';
+if(getPackageType(url)==='module'&&ext===''){
+constconfig=getPackageScopeConfig(url);
+constfileBasename=basename(filepath);
+constrelativePath=StringPrototypeSlice(relative(config.pjsonPath,filepath),1);
+suggestion='Loading extensionless files is not supported inside of '+
+'"type":"module" package.json contexts. The package.json file '+
+`${config.pjsonPath} caused this "type":"module" context. Try `+
+`changing ${filepath} to have a file extension. Note the "bin" `+
+'field of package.json can point to a file with an extension, for example '+
+`{"type":"module","bin":{"${fileBasename}":"${relativePath}.js"}}`;
+}
+thrownewERR_UNKNOWN_FILE_EXTENSION(ext,filepath,suggestion);
 }
 
 returngetLegacyExtensionFormat(ext)??null;

lib/internal/modules/esm/resolve.js

@@ -80,10 +80,10 @@ const DEFAULT_CONDITIONS_SET = new SafeSet(DEFAULT_CONDITIONS);
  * @typedef {'module' | 'commonjs'} PackageType
  * @typedef {{
  * pjsonPath: string,
- * exports?: ExportConfig;
- * name?: string;
- * main?: string;
- * type?: PackageType;
+ * exports?: ExportConfig,
+ * name?: string,
+ * main?: string,
+ * type?: PackageType,
  * }} PackageConfig
  */
 

test/es-module/test-esm-unknown-or-no-extension.js

@@ -31,6 +31,10 @@ const assert = require('assert');
 assert.strictEqual(code,1);
 assert.strictEqual(signal,null);
 assert.strictEqual(stdout,'');
-assert.ok(stderr.indexOf('ERR_UNKNOWN_FILE_EXTENSION')!==-1);
+assert.ok(stderr.includes('ERR_UNKNOWN_FILE_EXTENSION'));
+if(fixturePath.includes('noext')){
+// Check for explanation to users
+assert.ok(stderr.includes('extensionless'));
+}
 }));
 });