From f36fcb3b1216a761214ae1779f72576f5a45c549 Mon Sep 17 00:00:00 2001
From: aadamcik <adamcikado@gmail.com>
Date: Sun, 1 Feb 2026 10:48:13 +0000
Subject: [PATCH] fix: import .tsx using import mapping

---
 src/loader.ts        | 29 ++++++++++++++++----------
 tests/loader.spec.ts | 48 ++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 66 insertions(+), 11 deletions(-)

diff --git a/src/loader.ts b/src/loader.ts
index 9b7945b..6aa3376 100644
--- a/src/loader.ts
+++ b/src/loader.ts
@@ -112,22 +112,29 @@ export const resolve: ResolveHook = async (specifier, context, nextResolve) => {
      * production build.
      */
     if (error.code === 'ERR_MODULE_NOT_FOUND' && error.url && isLocalPath(error.url)) {
-      let [urlPathname, ...urlQs] = error.url.split('?')
+      let [urlPathname, ...urlQs] = (error.url as string).split('?')
       const fileExtension = extname(urlPathname)
+      const testExtensions: string[] = []
+
+      if (['.js', '.mjs', '.cjs', '.jsx'].includes(fileExtension)) {
+        testExtensions.push(fileExtension.replace('js', 'ts'))
+      }
 
       if (fileExtension === '.js') {
-        urlPathname = urlPathname.replace('.js', '.ts')
-      } else if (fileExtension === '.mjs') {
-        urlPathname = urlPathname.replace('.mjs', '.mts')
-      } else if (fileExtension === '.cjs') {
-        urlPathname = urlPathname.replace('.cjs', '.cts')
-      } else if (fileExtension === '.jsx') {
-        urlPathname = urlPathname.replace('.jsx', '.tsx')
+        testExtensions.push('.tsx')
       }
 
-      const url = urlQs.length ? `${urlPathname}?${urlQs.join('?')}` : urlPathname
-      debug('retrying to resolve file with specifier %s', url)
-      return nextResolve(url, context)
+      for (const ext of testExtensions) {
+        const tryPath = urlPathname.slice(0, -fileExtension.length) + ext
+
+        try {
+          const url = urlQs.length ? `${tryPath}?${urlQs.join('?')}` : tryPath
+          debug('retrying to resolve file with specifier %s', url)
+          return await nextResolve(url, context)
+        } catch {
+          // ignore and try next extension
+        }
+      }
     }
 
     throw error
diff --git a/tests/loader.spec.ts b/tests/loader.spec.ts
index 7f5e5f1..785a168 100644
--- a/tests/loader.spec.ts
+++ b/tests/loader.spec.ts
@@ -707,4 +707,52 @@ test.group('Loader', (group) => {
     assert.equal(result.stdout.trim(), '5000')
     assert.equal(result.stderr.trim(), '')
   })
+
+  test('allow importing files with .tsx extension using import mapping', async ({ assert, fs }) => {
+    await fs.createJson('tsconfig.json', {
+      compilerOptions: {
+        rewriteRelativeImportExtensions: true,
+        jsx: 'react-jsx',
+        jsxImportSource: 'preact',
+      },
+    })
+
+    await fs.createJson('package.json', {
+      imports: {
+        '#components/*': './components/*.js',
+      },
+    })
+
+    await fs.create(
+      'index.ts',
+      `
+      import render from 'preact-render-to-string'
+      import { Button } from '#components/button'
+
+      console.log(render(Button({ type: 'submit', text: 'Login' })))
+    `
+    )
+
+    await fs.create(
+      'components/button.tsx',
+      `
+      interface ChildrenProps {
+        type: 'submit' | 'button';
+        text: string
+      }
+
+      export function Button(props: ChildrenProps) {
+        return <button type={props.type}>{props.text}</button>
+      }
+    `
+    )
+
+    const result = await spawnPromisified(
+      process.execPath,
+      ['--no-warnings', '--import', './build/index.js', join(fs.basePath, 'index.ts')],
+      {}
+    )
+
+    assert.equal(result.stdout.trim(), '<button type="submit">Login</button>')
+  })
 })