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What is cross-site scripting (XSS) and how do I prevent it with JavaScript?

Asked on Aug 26, 2025

Answer

Cross-site scripting (XSS) is a security vulnerability that allows attackers to inject malicious scripts into web pages viewed by other users. Preventing XSS involves sanitizing and validating user input to ensure no harmful scripts are executed.

// Function to escape potentially dangerous characters
        function escapeHTML(input) {
            const div = document.createElement('div');
            div.appendChild(document.createTextNode(input));
            return div.innerHTML;
        }

        // Example usage
        const userInput = "<script>alert('XSS');</script>";
        const safeInput = escapeHTML(userInput);
        console.log(safeInput); // Outputs: &lt;script&gt;alert('XSS');&lt;/script&gt;

Additional Comment:

The "escapeHTML" function creates a temporary DOM element to safely encode HTML entities.
This approach prevents scripts from being executed by converting them into harmless text.
Always validate and sanitize user inputs on both client and server sides for robust security.
Consider using libraries or frameworks that automatically handle XSS protection.

✅ Answered with JavaScript best practices.

Ask any question about JavaScript here... and get an instant response.

What is cross-site scripting (XSS) and how do I prevent it with JavaScript?

Asked on Aug 26, 2025

Answer

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