codeharborhub · ajay-dhangar · May 6, 2026 · gemini-code-assist · May 6, 2026
@@ -43,6 +43,18 @@ app.use((err, req, res, next) => {
 });
 ```
 
+:::info Security Tip
+Exposing the error message directly to the client can leak sensitive information about the server's internal state. It is safer to only include detailed error information when the application is running in a development environment.
+
+```javascript title="server.js"
+  res.status(500).json({  
+    success: false,  
+    message: "Internal Server Error",  
+    error: process.env.NODE_ENV === 'development' ? err.message : {}  
+  });  
+```
+:::
+
 ## 3. Throwing Custom Errors
 
 Sometimes, the code isn't "broken," but the user did something wrong (like entering the wrong password). In these cases, you can "throw" your own error to trigger the catch block.

@@ -93,6 +93,32 @@ npm install -g nodemon
 nodemon server.js
 ```
 
+:::info
+Installing packages globally with `-g` is generally discouraged for project-specific tools. It is better to install nodemon as a development dependency to ensure that all developers working on the project use the same version.
+
+```bash
+npm install --save-dev nodemon
+```
+
+Then, you can add a script to your `package.json`:
+
+```json title="package.json"
+{
+  "scripts": {
+    "dev": "nodemon server.js"
+  }
+}
+```
+
+Now you can start your server with:
+
+```bash
+npm run dev
+```
+
+This way, everyone on the project will have the same version of nodemon, and you won't run into issues if someone doesn't have it installed globally.
+:::
+
 ## Practice: The Dynamic Greeter
 
 Let's use **URL Parameters** to greet users by name!

@@ -88,6 +88,21 @@ exports.getProfile = async (req, res) => {
 };
 ```
 
+:::info
+The `async` controller function lacks error handling. If the database call fails, the promise will reject without being caught, which can lead to unhandled promise rejections. It is best practice to wrap the logic in a `try...catch` block and pass the error to the `next` middleware.
+
+```javascript title="userController.js"
+exports.getProfile = async (req, res, next) => {  
+    try {  
+        const userData = await User.findById(req.params.id);  
+        res.json(userData);  
+    } catch (error) {  
+        next(error);  
+    }  
+};
+```
+:::
+
 **3. The Model (`/models/userModel.js`):** The definition of the data.
 
 ```javascript title="userModel.js"

@@ -92,6 +92,20 @@ fs.readFile('note.txt', 'utf8', (err, data) => {
 });
 ```
 
+:::info Error Handling
+In the above example, if `note.txt` does not exist, the `err` object will contain the error details. Throwing an error inside an asynchronous callback will cause the Node.js process to crash. Instead of throwing, you should log the error or handle it gracefully to keep the server running.
+
+```javascript title="readFile.js"
+fs.readFile('note.txt', 'utf8', (err, data) => {  
+  if (err) {  
+    console.error("Error reading file:", err);  
+    return;  
+  }  
+  console.log("File content:", data);  
+});
+```
+:::
+
 ## Practice: The Greeting Machine
 
 1.  Create a file named `greet.js`.

@@ -118,11 +118,11 @@ router.get('/all', (req, res) => {
 router.get('/:id', (req, res) => {
   const bookId = req.params.id;
   // In a real app, you'd fetch the book from the database
-  if (bookId == 1) {
-    res.json({ id: 1, title: "The Great Gatsby" });
-  } else if (bookId == 2) {
-    res.json({ id: 2, title: "To Kill a Mockingbird" });
-  } else {
+  if (bookId === "1") {  
+    res.json({ id: 1, title: "The Great Gatsby" });  
+  } else if (bookId === "2") {  
+    res.json({ id: 2, title: "To Kill a Mockingbird" });  
+  } else {  
     res.status(404).send("Book not found!");
   }
 });