How do you improve usability and security with client-side validation?

1 Benefits of client-side validation

Client-side validation can enhance the user experience of your web applications by providing immediate and clear feedback on the input fields. For example, you can use client-side validation to show error messages, highlight invalid inputs, disable submit buttons, or suggest auto-completion options. This way, you can help the user correct their mistakes, avoid frustration, and save time. Client-side validation can also reduce the server load by filtering out invalid or incomplete requests. This can improve the performance and scalability of your web applications, especially if they handle a large number of users or data. Moreover, client-side validation can prevent some types of malicious attacks, such as cross-site scripting (XSS) or SQL injection, by sanitizing or escaping the user input before sending it to the server.

2 Limitations of client-side validation

Client-side validation is not a substitute for server-side validation. You should always validate the user input on the server as well, because client-side validation can be bypassed, modified, or disabled by the user or by malicious actors. For example, the user can change the input values using the browser's developer tools, disable JavaScript, or use a proxy or a curl command to send requests to the server. Therefore, you should not rely on client-side validation for critical or sensitive data, such as authentication, authorization, or payment information. You should also not use client-side validation to enforce business rules or logic, such as pricing, discounts, or availability, because they can be easily manipulated by the user.

3 Best practices for client-side validation

To use client-side validation effectively and securely in your web applications, you should follow some best practices. Leverage HTML5 attributes and constraints to perform basic validation, such as required, pattern, min, max, or type. For custom or complex validation, such as email, password, or date format, use JavaScript or a library like jQuery Validate. It's also important to use event.preventDefault() or return false to prevent the form from submitting if the validation fails. Additionally, utilize encodeURIComponent() or escape() to encode or escape the user input before sending it to the server. Finally, use HTTPS and SSL certificates to encrypt the communication between the browser and the server. Client-side validation is a powerful technique to improve the usability and security of your web applications; however, it should always be complemented with server-side validation and best practices to avoid common pitfalls. With these measures in place, you can create web applications that are user-friendly, performant, and secure.

4 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?