How Can I Securely Verify AJAX Requests in PHP?

Determining AJAX Requests Securely in PHP

Server-side verification of AJAX requests is crucial for ensuring the validity of these requests. While common methods such as GET parameters and custom headers can be exploited, a secure approach involves checking the presence and value of the 'HTTP_X_REQUESTED_WITH' header.

To effectively implement this method, you can utilize the following code:

<code class="php">if (strtolower($_SERVER['HTTP_X_REQUESTED_WITH'] ?? '') === 'xmlhttprequest') {
    // This indicates an AJAX request
}</code>

This code checks if the 'HTTP_X_REQUESTED_WITH' header is set and its value is 'xmlhttprequest', which is typically associated with AJAX requests. By using the '??' coalescing operator, you can handle the case where the header is not set by assigning an empty string ('') to it.

By employing this approach, you can reliably determine whether a request is an AJAX request without compromising security.

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