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JavaScript Security
Published on 3/24/2026I don't know about you, but I started my career as a front-end developer working in a small agency, where no one cared about security. When I changed to work with bigger projects in bigger companies I kept not caring about security because no one had taught me better, and it led me to trouble. Understanding how to secure your JavaScript code can change that and help us to protect our applications and users. This article will explore some security practices that couldn’t hurt JavaScript developers to implement whenever they make sense. Some of the topics above I learned while studying the topic, but there are more ways to make your code safe. I am just sharing some simple ones to get you started.. P.S. Yes, I asked questions to an AI and asked it to help me with examples. P.S.2 Yes, IA created the cover image as I know my weaknesses LOL 1. Keep Your Dependencies Up-to-Date Outdated libraries can expose your applications to security vulnerabilities. Keeping everything up-to-date helps you avoid known issues that have already been fixed. Use a Package Manager: npm (Node Package Manager) is a great tool that helps you manage and update your libraries. Regular Checks: Run npm outdated to see which packages are outdated. Update Regularly: Use npm update to upgrade your packages to the latest versions. npm update # Updates your packages Automate Security Updates: Tools like npm audit identify and suggest fixes for security vulnerabilities. npm audit fix # Fixes packages with known vulnerabilities 2. Use Simple Security Headers Security headers tell the browser how to behave when handling your site's content, which helps prevent some types of attacks like cross-site scripting and data injection. We can use Content Security Policy (CSP), a security header that helps stop unauthorized scripts from running on your site, which can prevent many attacks. Start Simple: Add a basic CSP header that only allows scripts from your site. <!-- Add to the <head> section of your HTML --> <meta http-equiv="Content-Security-Policy" content="script-src 'self';"> This line means only scripts that are part of your website can be executed, not any from elsewhere. 3. Sanitize User Input User input can be dangerous if not handled correctly. Malicious users might try to input data that could harm other users or your site. We should always treat input as untrusted, cleaning the data coming from users to make sure it's safe before using it in your application. When updating the web page with user input, use textContent instead of innerHTML to avoid executing harmful scripts. const userInput = document.querySelector('#user-input').value; document.getElementById('output').textContent = userInput; // Safely add user content to your page And we are safer now friends… These three steps are a great starting point for securing your JavaScript applications. I hope you will take a moment today to review your JavaScript projects. Check for outdated libraries, ensure you're using security headers, and verify that all user inputs are sanitized. Small steps can make a big difference in the security of your web applications., plus, knowing these things will be a differential in your next interview ;) Speaking of Front-End… We have this super cool project we are building that will change the way you do web development 😯