How can I securely handle sensitive data in client-side JavaScript to prevent XSS attacks?

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How can I securely handle sensitive data in client-side JavaScript to prevent XSS attacks?

Asked on Jan 05, 2026

Answer

To securely handle sensitive data in client-side JavaScript and prevent XSS attacks, it's important to sanitize and encode any data that will be inserted into the DOM. Here's a simple example of how to safely insert user input into a webpage.

<!-- BEGIN COPY / PASTE -->
        function sanitizeInput(input) {
            const div = document.createElement('div');
            div.textContent = input;
            return div.innerHTML;
        }

        const userInput = "<script>alert('XSS');</script>";
        const safeInput = sanitizeInput(userInput);

        const outputElement = document.getElementById('output');
        outputElement.innerHTML = safeInput;
        <!-- END COPY / PASTE -->

Additional Comment:

This example uses a DOM element to automatically escape HTML special characters, preventing script execution.
Always use "textContent" or "innerText" for setting text, and avoid "innerHTML" unless the content is sanitized.
Never trust user input; always sanitize and validate it before using it in your application.
Consider using libraries like DOMPurify for more comprehensive sanitization needs.

✅ Answered with JavaScript best practices.

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How can I securely handle sensitive data in client-side JavaScript to prevent XSS attacks?

Asked on Jan 05, 2026

Answer

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