Added support up to Node.js v24.16.0 and troubleshooting instructions

README.md

@@ -34,10 +34,29 @@ If you want to use this REPL by default, you can point
 `NODE_REPL_EXTERNAL_MODULE` to the result of
 `which node-prototype-repl`!
 
+#### Troubleshooting
+
+If the above steps don't work, before running `node-prototype-repl`,
+simply clone this repo, navigate to it and run
+
+```sh
+npm install
+npm link
+```
+
+### Using as default Node.js REPL
+
+Point environment variable `NODE_REPL_EXTERNAL_MODULE` to the result of `which node-prototype-repl`
+or, on Windows, `where node-prototype-repl`
+
+#### Troubleshooting
+
+If it doesn't work, then point `NODE_REPL_EXTERNAL_MODULE` to `<your_local_git_repo_clone_path>/src/index.js`
+
 ## Contributing
 
 See [CONTRIBUTING.md](./CONTRIBUTING.md).
 
 ## License
 
-MIT. See [LICENSE](./LICENSE).
+MIT. See [LICENSE](./LICENSE).

src/index.js

@@ -438,25 +438,44 @@ Prototype REPL - https://github.com/nodejs/repl
   }
 }
 
-const child = spawn(process.execPath, [
-  '--inspect-publish-uid=http',
-  ...process.execArgv,
-  require.resolve('./stub.js'),
-  ...process.argv,
-], {
-  cwd: process.cwd(),
-  windowsHide: true,
-});
-
-child.stdout.on('data', (data) => {
-  process.stdout.write(data);
-});
-
-child.stderr.on('data', (data) => {
-  const s = data.toString();
-  if (s.startsWith('__DEBUGGER_URL__')) {
-    start(s.split(' ')[1]);
-  } else if (s !== 'Debugger attached.\n') {
-    process.stderr.write(data);
-  }
-});
+const net = require('net');
+
+function findAvailablePort(startPort = 9229) {
+  return new Promise((resolve, reject) => {
+    const server = net.createServer();
+    server.listen(startPort, '127.0.0.1', () => {
+      const port = server.address().port;
+      server.close(() => resolve(port));
+    });
+    server.on('error', (err) => {
+      if (err.code === 'EADDRINUSE') {
+        resolve(findAvailablePort(startPort + 1));
+      } else {
+        reject(err);
+      }
+    });
+  });
+}
+
+findAvailablePort().then(port => {
+  const child = spawn(process.execPath, [
+    `--inspect=${port}`,
+    `--inspect-publish-uid=http`,
+    require.resolve('./stub.js'),
+    ...process.argv,
+  ], {
+      cwd: process.cwd(),
+      windowsHide: true,
+  });
+  child.stdout.on('data', (data) => {
+    process.stdout.write(data);
+  });
+  child.stderr.on('data', (data) => {
+    const s = data.toString();
+    if (s.startsWith('__DEBUGGER_URL__')) {
+      start(s.split(' ')[1]);
+    } else if (s !== 'Debugger attached.\n') {
+      process.stderr.write(data);
+    }
+  });
+});

src/stub.js

@@ -5,7 +5,22 @@ const path = require('path');
 const inspector = require('inspector');
 const util = require('util');
 
-inspector.open(0, true);
+// Handle inspector.open() API differences across Node.js versions
+if (!inspector.url()) {
+  try {
+    // Try Node.js v24+ API (host, port)
+    inspector.open(9229, '127.0.0.1');
+  } catch (err) {
+    // Fall back to Node.js v20 and below API (fd, host, port)
+    try {
+      inspector.open(0, 'localhost', 9229);
+    } catch (fallbackErr) {
+      // If both fail, continue without debugger
+      console.error('Failed to open inspector:', fallbackErr.message);
+    }
+  }
+}
+
 process.stderr.write(`__DEBUGGER_URL__ ${inspector.url()}`);
 
 if (process.platform !== 'win32') {