header-middleware-next/src/utils/checkAjax.js

A lightweight and flexible middleware utility for managing HTTP headers in Next.js applications. Supports header extraction, transformation, masking, and safe injection for Edge and API routes.

/**
 * Function to check if an incoming HTTP request is an AJAX request.
 * It inspects the 'x-requested-with' header, which is commonly set by AJAX calls.
 *
 * @param {Object} req - The HTTP request object, expected to have a 'headers' property.
 * @returns {Object} - An object containing the result type, name, and message indicating AJAX detection status.
 */
export default async function checkAjax(req) {
    // Retrieve the 'x-requested-with' header from the request headers
    const requestedWith = req.headers['x-requested-with'];

    // Validate if the request is an AJAX request by comparing the header value to 'XMLHttpRequest'
    if (requestedWith !== 'XMLHttpRequest') {
        // Return info object when the request is NOT identified as AJAX
        return {
            type: 'info',
            name: 'AJAX',
            message: 'Request is not an AJAX call'
        };
    }

    // Return success object when the request is confirmed as AJAX
    return {
        type: 'success',
        name: 'AJAX',
        message: 'AJAX request detected'
    };
}