Javascript-Ajax Problems

When the client sends an ajax request to the server, where does the request go before it is included in the PHP script file on the server? When the client sends an ajax request to the server, where does the request go before it is included in the PHP script file on the server?

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When the client sends an ajax request to the server, where does the request go before it is included in the PHP script file on the server?

Route, that is, your controller layer. Here we will analyze the url Processing. AJAX also initiates a request. Therefore, after parsing the request, find the corresponding processing method, that is, the corresponding PHP script. if any, please advise

Personal Understanding: To put it bluntly, it is the same as entering a link in the address bar for access, all of which are http requests.