10 Common Mistakes Node.js Developers Make and How to Avoid Them

10 Common Mistakes Node.js Developers Make and How to Avoid Them

Node.js is powerful and flexible, but it’s easy to make mistakes that slow things down or cause security issues. Let’s look at 10 common mistakes developers make—and how to avoid them with simple code examples 😉👌😉

Let's Dive IN

1. Blocking the Event Loop

The Node.js event loop is single-threaded. Writing synchronous code can block the event loop, making your application unresponsive.

Mistake:

// Blocking the event loop with a synchronous loop
function performHeavyComputation() {
  for (let i = 0; i < 1e9; i++) {
    // Simulating heavy computation
  }
}
performHeavyComputation();
console.log('This will execute only after the loop finishes');

Solution: Offload heavy computations to a worker thread or use asynchronous approaches.

const { Worker } = require('worker_threads');

async function performHeavyComputationAsync() {
  try {
    return await new Promise((resolve, reject) => {
      const worker = new Worker('./worker.js');
      worker.on('message', resolve);
      worker.on('error', reject);
    });
  } catch (error) {
    console.error('Error in worker thread:', error);
  }
}

performHeavyComputationAsync().then(() => {
  console.log('Heavy computation completed');
});

2. Not Handling Errors Properly

Unhandled errors can crash your application.

Mistake

const fs = require('fs');

fs.readFile('/nonexistent-file', (err, data) => {
  if (err) throw err; // Can crash the app
  console.log(data);
});

Solution: Always handle errors gracefully.

fs.readFile('/nonexistent-file', (err, data) => {
  if (err) {
    console.error('File not found:', err.message);
    return;
  }
  console.log(data);
});

3. Hardcoding Configuration Values

Hardcoding values makes your application inflexible and insecure.

Mistake:

const dbPassword = 'hardcoded_password';

Solution: Use environment variables and libraries like dotenv.

require('dotenv').config();
const dbPassword = process.env.DB_PASSWORD;

4. Using Outdated Packages

Outdated dependencies can expose your app to vulnerabilities.

Solution:

• Regularly update dependencies using npm outdated and npm update.
• Use tools like npm audit to identify and fix vulnerabilities.

5. Improper Use of async/await

Incorrect usage of async/await can lead to sequential execution where parallel execution is possible.

Mistake:

async function fetchData() {
  await fetchFromAPI1();
  await fetchFromAPI2();
}

Solution: Use Promise.all for parallel execution.

async function fetchData() {
  await Promise.all([fetchFromAPI1(), fetchFromAPI2()]);
}

6. Overusing Global Variables

Global variables can lead to unexpected behavior in large applications.

Mistake:

global.config = { appName: 'MyApp' };

Solution: Use module exports instead.

module.exports = { appName: 'MyApp' };

7. Lack of Input Validation

Failing to validate input can expose your app to security threats like SQL injection.

Mistake:

app.post('/login', (req, res) => {
  const query = `SELECT * FROM users WHERE username = '${req.body.username}'`;
  db.query(query, (err, result) => {
    if (err) throw err;
    res.send(result);
  });
});

Solution: Use parameterized queries.

app.post('/login', async (req, res) => {
  try {
    const query = 'SELECT * FROM users WHERE username = ?';
    db.query(query, [req.body.username], (err, result) => {
      if (err) {
        console.error('Database error:', err);
        return res.status(500).json({ error: 'Internal Server Error' });
      }

      if (result.length === 0) {
        return res.status(404).json({ error: 'User not found' });
      }

      res.json(result);
    });
  } catch (error) {
    console.error('Unexpected error:', error);
    res.status(500).json({ error: 'Something went wrong' });
  }
});

8. Poor Database Query Optimization

Inefficient queries can slow down your app.

Solution:

• Use proper indexing.
• Use query optimization tools provided by your database.
• Avoid N+1 query problems by batching queries where possible.

9. Not Using a Process Manager

Running your app directly with node app.js doesn’t handle crashes or restarts.

Solution: Use a process manager like PM2.

npm install pm2 -g
pm2 start app.js

10. Ignoring Logging and Monitoring

Lack of proper logging makes it hard to debug issues in production.

Solution: Use logging libraries like winston or pino and monitoring tools like New Relic or Datadog.

const winston = require('winston');

const logger = winston.createLogger({
  level: 'info',
  format: winston.format.json(),
  transports: [
    new winston.transports.Console(),
    new winston.transports.File({ filename: 'error.log', level: 'error' }),
  ],
});

logger.info('Application started');

Node.js is powerful but can be tricky to get right. Avoiding these common mistakes will make your applications more robust, scalable, and secure. If there’s any concept you don’t fully understand, feel free to ask in the comments! Also, drop a like if you found this helpful. Let’s learn together!