Essential Strategies for Handling Errors and Exceptions in Node.js Applications

Proper error and exception handling is critical for building stable Node.js applications. Here’s how you can handle errors effectively:

1. Use Try-Catch for Synchronous Code

• Useful for code that doesn’t use callbacks or Promises.
• Example:

try {
  // Synchronous code that may throw
  let data = fs.readFileSync('file.txt');
} catch (err) {
  console.error('Error reading file:', err);
}

2. Handle Errors in Callbacks

• Always check for the first err argument in callbacks.
• Example:

fs.readFile('file.txt', (err, data) => {
  if (err) {
    console.error('Error:', err);
    return;
  }
  console.log('File data:', data);
});

3. Manage Promises and Async/Await Errors

• Use .catch() for Promises and try-catch for async functions.
• Example:

// Promise
readFileAsync('file.txt')
  .then(data => console.log(data))
  .catch(err => console.error('Promise error:', err));

// Async/Await
async function readFile() {
  try {
    let data = await readFileAsync('file.txt');
    console.log(data);
  } catch (err) {
    console.error('Async/Await error:', err);
  }
}

4. Handle Uncaught Exceptions and Unhandled Rejections

• Use process events to log and shut down gracefully.
• Example:

process.on('uncaughtException', err => {
  console.error('Uncaught Exception:', err);
  process.exit(1);
});

process.on('unhandledRejection', reason => {
  console.error('Unhandled Rejection:', reason);
  process.exit(1);
});

5. Use Error Middleware in Express

• Handle errors efficiently in web APIs.
• Example:

app.use((err, req, res, next) => {
  console.error(err.stack);
  res.status(500).send('Something broke!');
});

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Summary: Always handle errors at every layer—synchronous, callback, promise, and process level. This keeps your Node.js applications resilient and maintainable.