What are the best ways to secure your HTML5 code?

1 Validate your input

One of the most common and dangerous security threats for web applications is injection, which occurs when an attacker inserts malicious code or commands into your input fields or URL parameters. This can compromise your database, server, or client-side logic, and expose sensitive data or execute unauthorized actions. To prevent injection, you should always validate your input before processing it, and use proper escaping, encoding, or sanitization methods. You should also use parameterized queries or prepared statements instead of concatenating strings when interacting with your database.

2 Use HTTPS and SSL

Another common security threat for web applications is interception, which occurs when an attacker intercepts or modifies the data that is sent or received between your website and your users. This can compromise your users' privacy, identity, or credentials, and expose them to phishing, malware, or man-in-the-middle attacks. To prevent interception, you should always use HTTPS (Hypertext Transfer Protocol Secure) and SSL (Secure Sockets Layer) to encrypt the communication between your website and your users. HTTPS and SSL ensure that only the intended parties can access and verify the data, and that no one can tamper with it.

3 Implement CSP and SRI

HTML5 introduces some new features that allow you to embed external resources or scripts into your web pages, such as <iframe>, <video>, <audio>, <canvas>, and <script>. However, these features also increase the risk of cross-site scripting (XSS), which occurs when an attacker injects malicious code or scripts into your web pages that run in your users' browsers. This can compromise your users' session, cookies, or local storage, and execute unauthorized actions on your behalf. To prevent XSS, you should implement CSP (Content Security Policy) and SRI (Subresource Integrity). CSP is a header that tells the browser what sources of content are allowed or blocked on your web pages, and SRI is an attribute that tells the browser how to verify the integrity of the external scripts or resources that you load.

4 Secure your storage

HTML5 provides some new features that allow you to store data locally on your users' browsers, such as localStorage, sessionStorage, and IndexedDB. These features can enhance your website's performance, functionality, and user experience, especially for offline or progressive web applications. However, these features also pose some security risks, as the data stored locally can be accessed or modified by other scripts or applications on the same origin or domain. To secure your storage, you should encrypt the data that you store locally, and use secure tokens or cookies to authenticate your users. You should also limit the amount and type of data that you store locally, and clear the data when it is no longer needed.

5 Update your libraries

HTML5 relies on various libraries and frameworks to provide additional features and functionality for your web applications, such as jQuery, Bootstrap, Angular, React, and Vue. These libraries and frameworks can simplify your development process, improve your code quality, and enhance your user interface. However, they can also introduce some security vulnerabilities or bugs that can be exploited by attackers. To update your libraries, you should always use the latest versions of the libraries and frameworks that you use, and check for any security patches or updates that are released. You should also remove any unused or outdated libraries and frameworks from your code, and use minified or compressed versions of the libraries and frameworks that you use.

6 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?