JQuery and other frameworks add the following header:
X-Requested-With: XMLHttpRequest
Why is this needed? Why would a server want to treat AJAX requests differently than normal requests?
UPDATE: I just found a real-life example using this header: https://core.spreedly.com/manual/payment-methods/adding-with-js. If the payment processor is requested without AJAX, it redirects back to the original website when it’s done. When it is requested with AJAX, no redirection is done.